If you record some audio and upload it, then log into the site on iphone, and click to view the audio file it comes up that it cannot play.
Perhaps if it is an iphone Moodle could detect this and do appropriate headers for it?
I notice that the Accept-Ranges: none is being used rather than the Accept-Ranges: bytes
Also, with the Content-Disposition: attachment; filename="2011-09-12 212035 +0000.mp4" does this impact it as well?
I know its technically the Moodle install side issue, but if people are adding the content from phone... sorry if its in wrong place.