Recently I often watch nicovideo, which is the Japanese streaming video, because this is a very interesting video site. Unfortunately, you can't view this site unless you register, but I can introduce it.
The greatest feature of nicovideo is, you can add comments "into" the video directly, just like the words in the picture below.
I like this site because combining video and real time comment is a great idea. You can know how other people feel when you are watching, and you can add your opinion, too. However, when the video is famous, there will be many words on the screen and block your sight. And also, because everyone can post comment, there is no way to control what they can say. At least for Japanese people, I don't think they would like to see any Chinese or Korean on it. In this case, nicovideo need to improve the interface. Nicovideo needs account to login, but it won't show their ID when commenting. It might be a good way to let everyone know who is talking so that they can tell the administrator to stop some impolite behaviors.
In fact, nicovideo is still testing now, and the amount of user is limited. So far I'm very comfortable to watch video with many words. I will be glad to see if there is a better system for them to improve.