1080p working just fine here with flash, and 720p with html5 (1080p html5 probably work just as fine, but Firefox doesn't support dash so I can't test it).
Originally Posted by kernelOfTruth
But I'm not sure if it's using hardware acceleration or just failing back to software, I have a somewhat beefy cpu (i7-860) so I usually just don't notice.
P.s. with KWin, I used to get tearing on the desktop until I configured Desktop effects > Advanced > Tearing prevention to "Full Scene Repaint". But I don't remember having tearing with videos before that.