there is also FlashVideoReplacer. Play Youtube videos with any player you like
https://addons.mozilla.org/en-US/fir...videoreplacer/
On Ubuntu, Flash 11 had issues with tearing and frame drops.
Flash 10.3 had the same issues but after I enable hardware acceleration in the adobe.cfg file (not the Override GPU command), Youtube videos play smooth, showing both hardware decoding and hardware rendering. Flash 11 does not enable that option even with a modified adobe.cfg
On Windows is there a way to enable that option?