Oliver One replied at 2015-4-9 11:53
not sure if this works (don't want to enable html5 to test, in case I wouldn't be able to disable it again) :
right click on video you are watching, "about the html5 player", click on that, then part way down on left of screen use defaut player it disables html5.
or this : http://www.interleave-vr.com/youtube-proper-player.php