This is very simple extension to enable playing of certain embedded Youtube videos which usually would be blocked and not allowed to play. (i.e videos are blocked on certain websites and similar situations.) All it does is makes Youtube think that you playing all their videos from google.com domain.
[Disclosure] It doesn't allow you to play videos that are blocked in your country.
Extension is open sourced https://github.com/drulia/youtube_video_unblocker