Hello,
I just installed Jessie on one of my partitions. Most of the stuff works
just fine, but I'm having problem playing HTML5 videos on Youtube in
Iceweasel. I can't even watch webm videos from here:
http://ftp.acc.umu.se/pub/debian-meetings/2014/debconf14/webm/
It looks like video is playing in fast forward mode. No such problems in
Chromium and no problem in Wheezy on another partition. I installed all
packages that were installed in Wheezy, so I guess that all needed
codecs are installed.
Page at youtube.com/html5 shows that HTMLVideoElement, H.264 and WebM
VP8 are OK, but Media Source Extensions, MSE & H.264 and MSE & WebM VP9
are with red exclamation mark.