A few things I think are important regarding what you are saying :
Yep it works. You may still have a bug or two from times to times.
Here a screenshot of YouTube with flash, full screen and you can change the quality (click to enlarge) :
That file doesn't work either
Here I've uploaded the one I used on the tab S so this one I'm sure is working :
I should stop trying to show you how wrong you are but here you go, same thing with an LG Gpad 8.3 with CM11. No touchwizz here, so what's gonna be the next reason?