Somebody is working on VC-1 support for ffmpeg, which means WMV9/WMV3/VC-1 playback on Macs with programs that use libav* like MPlayer. I'm not sure how well it works yet, but you can try it out, if you build your MPlayer and replace the following code in libavcodec/allcodecs.c (should be about line 232):
Code:
/* Reenable when it stops crashing on every file, causing bug report spam.
#ifdef CONFIG_WMV3_DECODER
register_avcodec(&wmv3_decoder);
#endif //CONFIG_WMV3_DECODER
*/
With:
Code:
#ifdef CONFIG_WMV3_DECODER
register_avcodec(&wmv3_decoder);
#endif //CONFIG_WMV3_DECODER
I'm not sure whether you need to specify -vc +ffwmv3 to make mplayer use the codec. If it doesn't seem to find a codec for a WMV3 file, try that option.
Anyway, it seems to work pretty well for me (on Linux). If you want to try it, do so at your own risk.