Why would you break vdpau and cripple your graphic card drastically just because of Youtube?? This has to be the most insane suggestion I hear. :)
You don't need flash for Youtube! Here are a few alternatives (the bug affects only Youtube)
flashvideoreplacer, a Firfox addon
literna magica , a script that play videos without flash on many websites including Youtube
smplayer (latest from ppa has youtube player)
All use mplayer as backend (if you install gecko-mediaplayer and since you have Nvida card you get hardware acceleration with vdpau.
So it would be nice if adobe fix the problem, It is no big deal even if it doesn't.