When I'm watching videos on YouTube, I'm usually ignoring the comment section as it is filled with spam, immature contents and other comments that do not really add anything to the video that I'm watching.
It is not always the case though, especially if a channel author takes good care of the section by moderating comments regularly. This weeds out the majority of comments that should not really be there at all.
Google recognized the issue a long time ago but it took the company years to come up with a solution. It recently announced that it would switch to Google+ exclusively, which means that YouTube users who want to leave comments need a Google+ account to do so.
While I still think that this is yet another attempt to push the Google+ social networking service, it may lead to less comment spam on YouTube after all as a side-effect. It won't take care of the issue on the other hand.
YouTube video responses
YouTube did highlight video responses to videos in a special section on the page previously, but I'm not entirely sure if that is still the case. I have not seen a response section for some time now on the site.
The /watch Video Responder extension for the Firefox web browser improves the discovery of these responses. Without it, you have to go through all comments manually to find videos linked here by their authors. With the extension, you simply look on the right and see them all listed here so that you can click on them right away.
Note: Only the first 1000 comments are crawled by the extension due to YouTube API limitations.
The extension crawls the top 1000 comments on YouTube video pages automatically and lists every video response that it finds on the sidebar. Only video links by their authors, checked by comparing the username's of the comment poster and video author are displayed here. This takes care of YouTube links posted by non-authors.
All videos are displayed with their title, comment, video thumbnail and link. The extension checks for availability and will highlight videos that are no longer available in the sidebar. It would probably have been better if those were not displayed at all here, but it is better than nothing. This can be changed in the options though.
Partial video links, for instance those where only part of the url is posted, will be turned into links that you can click on by the extension. The extension adds an icon to Firefox's address bar that you can click on to display its options.
Here you can disable the highlighting of matched responses, or enable the prioritization of said responses.
If you like to watch follow-up videos on YouTube, then this extension may help you speed up the discovery process of video responses on the site. The add-on does not slow down the Firefox web browser or the video loading time, which is definitely a plus.