And this is a healthy reminder that when you mess with someone else platform without an actual API you have to test a lot... because you don't understand anything about the implementation; not to mention it could change anytime (especially something as experimental as HTML5 video tag).
1) It doesn't work in Youtube.com itself and it doesn't have anything to do with copyright but with the uploaders preferences (but yes, song owners sometimes enforce this setting on behalf of other users).
2) Many music videos are disabled; so call this a patch is technically inaccurate because it probably disables more videos than it enables wish is something that makes "gets the job done" a debatable statement.
3) To point out a bug doesn't mean I am willing or able to fix it; that is not how open-source works anyway.