I've tested on several installations of Safari 5.1.7 for Windows and I can't seem to get HTML5 videos to play.
I've been testing with this:
Basic HTML5 video test
It seems to work on Safari 5.1.7 for Mac and also earlier 5.0.x installations of Safari on Windows. Am I missing something?
Managed to fix this. For anyone else encountering similar problems, note that Safari requires quicktime in order to play HTML5 video/audio. If you've upgrade to a later version of Safari and notice that HTML5 video/audio stops working, you may also need to upgrade to the latest version of quicktime.