I do not blame you if you have never heard about Youku before. It is a Chinese video hosting website comparable to YouTube.
Thanks to its Chinese-only interface, it has likely flown under the radar for most users who do not speak Chinese.
What's rather interesting is that it is one of the top 100 sites of the Web according to Alexa, and while the stats are not exact in terms of traffic, it highlights that the site is very, very popular.
If you do take the time to explore what it has to offer, you may notice that it does offer quite the large selection of non-Chinese contents, especially in its TV and Movies sections.
Fans of US TV shows such as The Blacklist, Revenge, Almost Human and dozens of others will for instance notice that they are all available on the site, in English with Chinese subtitles.
And if you prefer shows from the UK, you are also covered here as shows such as Sherlock, Hit&Miss, Dowtown Abbey or The White Queen are available as well.
Besides TV contents, you will also find that Youku hosts an impressive number of movies that you can watch on the site. It is rather interesting to note that you find many top blockbusters on the site, including all Top 50 films on IMDB.
How that is possible? Likely because of how copyright is handled -- or ignored -- in China.
What you may also notice is that the shows are not available if you connect to the site from outside of mainland China.
While regular videos are available and can be viewed from any location in the world, some contents are limited and you will receive an error message when you try to access them. This is similar to how YouTube restricts contents on its website.
Tip: I suggest you use either Google Chrome to browse the website if you do not speak Chinese, as you can translate it to a language you speak then, or a browser and a translation add-on for it, for instance Google Translator for Firefox.
If you are from China and want to unblock Youku while you are traveling, then you can make use of the Google Chrome extension Unblock Youku to do so.
All you need to do then is click on the icon when a video on Youku does not play, and reload the page to have it play just fine for you.
The extension is easy to use and there is configuration whatsoever involved.
The stream quality and performance is fine, and if your Internet connection is fast enough, you should not notice any slow downs or buffering pauses while you stream contents to your system.