Force Flash video on YouTube in Firefox

Martin Brinkmann
Oct 20, 2014
Firefox, Firefox add-ons

When you visit the popular video hosting site YouTube in the recent version of Firefox, Adobe Flash is no longer being used by default to stream videos to the device.

HTML5 video is being used instead and there is no option on the site itself to change that. You were able to toggle between HTML5 and Flash video until recently on but that option is no longer available when you connect using the Firefox web browser (it is also not available in other browsers such as Google Chrome).

You can right-click on any video playing on the site to see whether Adobe Flash or YouTube is being used to stream that video.

YouTube may switch to Flash automatically but there is no option to control that manually without the use of add-ons or other tweaks.

The Firefox add-on YouTube Flash Video Player gives you an option to select which video player you want to use on the video hosting site.

youtube flash player switch

It is set to use Flash Player automatically and if you are okay with that you don't have to do anything after installation.

When you visit YouTube afterwards you will notice that Adobe's Flash Player is being used to stream the videos provided that it is installed on the system and active in the Firefox web browser.

The add-on places an icon in Firefox's main toolbar that you can use to switch between both players. It remembers the selection so that you only need to change it when you want to change the player again. If you don't want to change it, simply right-click on it and select to remove the icon from the toolbar as there is no need to keep it there in this case.

It is interesting to note that the selection works on YouTube itself and on third-party websites as well, at least on sites that I tested the add-on on.

The add-on can be useful to Firefox users who experience issues with the HTML5 player or prefer to use Flash instead of HTML5.

software image
Author Rating
4.5 based on 3 votes
Software Name
YouTube Flash Video Player
Landing Page

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  1. 99ways2die said on October 7, 2016 at 2:56 pm

    I have serious issues with HTML5 myself so the people that said he shouldn’t be promoting this can kiss my a**. By choice I still run an old OS because of believe it or not the security in these new machines are garbage. I’m not at all impressed with 10’s,,, much of anything, Vista, was total trash and 7 was just a pain in the a** all the way around. Not being a gamer I really don’t need the newer bigger better stuff and I don’t want all my resources taken up for stuff I’ll never use.

    That being said I like the flash player allot better than the new players that I really see no more advantage to except to get you moved over to the new windows. I have the newest FireFox installed and still yet the only problem I seem to have is with the great and wonderful HTML5 player and nothing else?

    Pfft please, it’s to force onto some thing new and that’s it. Make them MONEY for the computer industry.

    This tool he is blogging about has nothing to do with free market, fact the fact the computer industry is trying to force everyone off flash is the real demolition of free market, maybe people need to get that through their trendy little thick skulls.

  2. FlashOVERHTML5 said on September 7, 2016 at 9:44 pm

    Thank you Martin Brinkmann.
    This was clear and helpful.

  3. bstecklum said on September 10, 2015 at 10:29 pm

    Small addendum. Just noticed that in FF full screen mode the hot upper border allows to switch back to normal view again. So no need for opening another tab.

  4. bstecklum said on September 10, 2015 at 10:15 pm

    Although it’s been a while since the last posting, I want to add some nifty advice. The URL trick of 4815162342 allows to play flash full screen by checking F11 in the browser view menu. Thereby, a long-standing flash bug (which was never considered by Adobe to be important) can be circumvented. In twinview video configuration, flash full screen always appears on the left screen, without any workaround yet. Now you can move the FF window to the right screen, check full screen view, and there you go. After the playback, click on the youtube link which opens the HTML5 player where you press F11 to leave full screen again. Enjoy!

  5. Robert Palmar said on October 20, 2014 at 7:16 pm

    I too have yet to encounter HTML5 on YouTube in Firefox 33.
    Why YouTube still defaults to Flash is a mystery at the moment.

  6. chesscanoe said on October 20, 2014 at 3:34 pm

    I seem to recall Google asked or told Firefox to support H265 by Fx 34 stable, due the end of November. In Fx33 I get switched to Flash automatically on some hidden error if I haven’t forced Flash in the first place with [Flash] per prior comment. This may be due to VLC settings but I haven’t been able to resolve this behavior so far.

  7. Uhtred said on October 20, 2014 at 1:40 pm

    on FF 33.0 visiting youtube I still get prompted to run adobe flash at present, I’ve not encountered any html5 yet… I wonder if being forced to html5 will mean my “download videos as mp4” plugin will still do the job. If not, this forcing flash plugin might well be useful.

  8. 4815162342 said on October 20, 2014 at 11:31 am
    1. mikecorbeil said on May 30, 2016 at 7:04 am

      The “[Flash]” link isn’t working. It’s now 30 May 2016, 12:55 am EST, and YouTube Flash Video Player was installed minutes ago. Firefox isn’t allowing the page be loaded for the Flash version of the video. When I right-click on the link and ask for the page to be loaded in a different tab, Firefox displays a pop-up dialogue asking what I want Ffx to do. The options are to “Open With” VLC media player, which is set as the default but which also is the sole video player option anyway; and the other option is to save the file. So, I cancel.

      The very same thing happens when I copy the link, open another tab, an empty one, paste the link in the address bar and then press Enter or Return to have the page loaded.

      This is very odd, given that the last update for the add-on is 2 May 2016. So, could Ffx’s absolute refusal to allow the video as Flash media be due to using Ffx 46.0.1 or because I’m also using Korora 23 Linux?

      I disabled the add-on, as well as the YouTube High Definition add-on, the latter having been suggested by the former; but, with the video page for the HTML5, I can see the tool icons in the toolbar of Ffx and checked the options, which’re to choose between Flash and HTML5. Switching it to HTML5 eliminates the problem described above.

      So, I’ll keep both installed and enabled until receiving replies for this post.

      1. mikecorbeil said on May 30, 2016 at 7:50 am

        Actually, a little light just came on inside of my head. The Adobe Flash plugin isn’t installed, for Adobe ceased supporting Linux some years ago, as I learned at after having recently had very serious problems due to having enabled the repository for Adobe, installed the Adobe Reader application, and tried using it. It messed my system bad enough that uninstalling the Reader didn’t help. I had to do a complete reinstallation of Korora 23 Linux to get a properly functional system again.

        The reason is that the downloaded Reader is rather very old, now, for Adobe fully ceased supporting Linux a few or more years ago.

        Hence, I’ll just uninstall YouTube Flash Video Player and the other add-on the latter recommends, YouTube High Definition. The Flash plugin for Ffx for Linux would be much too old, today.

        So, I’ll need to accept to have only HTML5 format videos at YouTube, but I learned yesterday evening of two add-ons for stopping auto-play at YouTube and other websites, and both extensions work with Ffx on Linux. They’re FlashStopper and “Flash Control” (with a space, unlike FlashControl for Chrome). Both add-ons are supposed to work for Flash as well as HTML5 videos, and both have good average ratings, 5/5 with 63 votes/reviews for FlashStopper, and 4/4 with 64 votes for Flash Control. And a nice thing about both is Firefox doesn’t need to be restarted.

    2. Martin Brinkmann said on October 20, 2014 at 2:09 pm

      This looks definitely useful. Thanks!

      1. CD said on October 21, 2014 at 2:21 am

        Ok, thank you. I did notice the url differences but just wasn’t sure if there was something else I was missing. Appreciate your response.

      2. chesscanoe said on October 20, 2014 at 8:30 pm

        I run Win7x64 Home on a 2 year old I5 laptop. On IE11, both HTML5 and Flash run very well on your example clip. On Fx33, Flash runs very well but HTML will not run at all unless I “Allow” all using NoScript. Even then, HTML5 jitters badly. FWIW….

      3. CD said on October 20, 2014 at 4:27 pm

        Would someone please explain this “useful” trick to those of us who aren’t quite so tech-savvy as others here?

      4. Martin Brinkmann said on October 20, 2014 at 4:34 pm

        Well it enables you to switch between the player by manipulating the url. Simply look at the address of the video you are on and change the url so that it uses the “other” structure.

        So, if the video is you modify it to to switch from HTML5 to Flash player.

  9. Tom said on October 20, 2014 at 11:18 am

    This just doesn’t happen for me.

    I have FF 33 and it still defaults to using Flash (also checked in safe mode). I tried clearing cookies. Media Source Extensions is enabled. What am I doing wrong?

  10. nuance said on October 20, 2014 at 10:32 am

    using flash plugin can lower the CPU usage rate than html5.

  11. Nickname said on October 20, 2014 at 10:12 am

    You could just disable certain preferences from about:config or switch your user agent.

  12. Pd said on October 20, 2014 at 9:56 am

    Unless people are experiencing real problems with the HTML5/OpenH264 scenario in Firefox, it’s quite disappointing to see you promoting use of arguably the last big proprietary plugin holding the open web back. Especially just days after your WebRTC article.

    1. Daniel said on May 2, 2015 at 12:11 pm

      Have you actually tried watching videos using the HTML5 player? Not just testing if it works and plays, but actually using it. Here are a few of the experiences I made while using HTML5 on YouTube (with Firefox 37.0.1 and an nVIDIA GPU on Win7 x64) for just one hour, before forcing the switch back to Flash:

      * MSE aren’t yet enabled in Firefox, which disables all DASH streams and means that you can’t go higher than 720p, and will run at much lower bitrates than what YouTube offers. It also means that videos are always buffered completely, which can be a problem for weaker systems and long HD videos.

      * The available streams have noticeably worse video and audio quality than what’s being played back by the Flash player. I guess the video degradation has something to do with the way they use hardware acceleration; I’m not yet sure how they managed to mess up the audio.

      * As of Firefox 37.0.1, scaling seems to be broken/disabled. Watching video on the site, lower resolutions are letterboxed and 720p exceeds the video frame and is cropped. Scaling doesn’t work on fullscreen either, videos are played back in the top left corner of the screen in whatever their native resolution is.

      * Compare CPU and memory usage when using the HTML5 player vs. the Flash player. Incredibly, they somehow managed to make HTML5 hog considerably more resources than Flash!

      It’s inexplicable to me how Mozilla could’ve decided to force this switch considering all of these unfixed, major issues (and I’m sure there are a lot more I simply didn’t encounter during my short trial run). It’s unfinished and broken software, plain and simple, and the least that Google could’ve done on their side is give users an official option to revert to the “legacy” version that at least works as intended.

    2. Neal said on October 20, 2014 at 10:43 pm

      Firefox doesn’t have Media Source extensions implemented yet, so HTML videos are either 360p or 720p. Even if you turn it on through about:config, it is a buggy mess. It is so far off from being properly implemented, it isn’t even turned on in Nightly, meaning at this rate, we won’t get it in stable until middle of late next year.

      There are still a ton of videos whose highest resolution is 480p, so meaning the html player will force 360p. IE, Chrome implemented MSE a long time ago. For a company who constantly harp and blame flash for most of their problems extolling the virtues of html5 players, Mozilla sure is taking it time.

      1. Chains The Bounty Hunter said on October 21, 2014 at 9:48 am

        I commented similarly re: MSE in Firefox. It honestly looks like very little developer effort is being focused on it, possibly for good reason I couldn’t venture to guess, and it’s something that needs to be remedied if they hope to fully push reliance on Flash out the door.

    3. fokka said on October 20, 2014 at 2:31 pm

      i’d rather see flash gone for good too, but as long as the html-player on youtube is unreliable and buggy for me, i’m very happy at least having the option to go back to flash.

    4. Martin Brinkmann said on October 20, 2014 at 10:10 am

      I’m not promoting anything but think that choice is always better than no choice.

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