And so is WMA and Apple did not provide support for it on thier players
Anyway, if you want support for AAC on WMP and thus through the streaming option you just need to get the codec for WMP right? Hmmm, I don't think Apple have made one of those available. Sigh, not so open then.
Flip for Mac, like I said will now play WMV HD clips (Although I can't confirm this 100% as my mini is not up to the job of playing those files).
I think the issue is the fact that is nothing to stream the files (video) over to the 360 from the mac.