I've discovered that AudioElement doesn't handle m4a files even though its entirely possible to play them in actionscript using NetStream. Here's the bug: http://bugs.adobe.com/jira/browse/FM-1014
I'm still rather new to OSMF but am thinking of either writing a plugin or contributing to the project by adding this functionality.
Where's the best place for me to start attacking and fixing this issue? Or has anyone else already solved this bug.