Using Opera I'm not able to play videos for some weeks now. This was confirmed by others on the village pump of de.wikipedia. After start playing the video it stops immediately (after playing a part of a second).
I don't really know what's the exact reason, but after some analyzing it seems to be a loading error. If I start watching a video with the mediawiki player, I'm even not able to play it afterwards in Opera (same problem with the internal player). But if I play the video first using Opera (and let Opera load the whole video), I can play it using the mediawiki player afterwards without any problems.
Other sites (YouTube, WebM test pages) don't have this error.
Version: master
Severity: major