Didn't apply to YC but interesting idea. I thought of the same idea but there was one fundamental problem I couldn't solve. That is, the text on the side is too distracting. I hope you can think of some ways to solve that problem!
That is one of the top problems! And I have many ideas. One of which is limit the number of comments by building a social networking feature where you only see the comments of people in your network. This could be Facebook, or it could be "Hacker News people" or IBM employees.
There's also user interface ways to make things less jarring.
Even if you limit the comment, it is still there on the side, which means you are still distracted. I would attack the problem from an UI and UX standpoint. I know there is a website or app (can't remember the name of the website) that shows the comment ON the video as the video plays, kinda like subtitles (you can turn it off). Nonetheless, it's still too distracting for me.
Here is an idea you can play with: wikipedia for videos. So sometimes after you watched a video, you want to know EVERYTHING about it, and usually the comment are crap for factual information about the video. What you can do with that technology is allow users to learn more about the video when he or she pauses or when the video ends. Lots of possibilities here =).
