Although the availability of my time to work on this project is sporadic at best, I do occasionally find time to make major upgrades. On that note, I have just release YouTube5 version 2.4.0, which includes several fixes and one major improvement. It fixes Vimeo support (although I am still encountering issues with some videos that I cannot figure out), and all the artwork in the player is now vector based (SVG), so it will look better when scaled up.
The major new feature is Pop-Out. Just click this icon:
And the player will pop out of the page and expand to fill most (or all) of the page.
Best of all, this will work on any website, not just YouTube.com. Tired of small embedded videos on your Facebook feed? Just pop them out to view them at a larger size, but without needing to go fullscreen.