Right, just for posterity, in case anyone's still interested, here's the asfdemux port I did.

It does stuff okay with local files, don't have too much luck with streams, but I can't tell whether that's asfdemux's or mmssrc's or whatever's fault. Seeking isn't exactly smooth but at least works.

I seem to remember that there's something stupid being done there with timestamps on video buffers somewhere, but I can't find the spot right now. Also, the audio descrambling stuff doesn't work (but then it didn't either in 0.8, but this version has a descrambling-related crash fixed at least IIRC).