My friendly match this week (742479563) is not playing back properly. I changed the audio extension to mp3, which solved the audio problem. I still have problems with the replays, as they only work after many attempts.
I'm just trying to reproduce your problem with firefox and firefox nightly right now but it seems to work without problems. A couple of weeks ago I got your issue but I got no time to make a deep analysis. Can you tell me if your problem is still present?
