I tried full screen on YouTube. The screen went full, YouTube posted a message that it was full screen, there was sound, BUT the screen stayed black.
Can any of you folks get fullscreen at YouTube? If so, what is my likely problem?
You can try by disabling hardware acceleration.
Set, through Edit>Configuration>browser configuration (aka about:config) the preference layers.acceleration.disabled to true.
It's better to have it disabled. At least in my side, doesn't mean anyting good.
sometimes it works, sometimes - not. I think, the difference hides itself in video hardware config and in the flashplayer version.
KM still handles youtube videos as Flash not HTML5 as I can see.
No, it handles in html5, just enable it at https://www.youtube.com/html5
. It just it isn't by default, even in Firefox.