River Past QuickTime DirectShow Filter for WMP let you play QuickTime, MPEG-4(MP4, M4V), DV and 3G (3gp and 3g2) video, MPEG-4(M4A) and AMR audio, animated GIF and FLC animations in Windows Media Player.
Compatibility
It is implemented as a DirectShow filter, using the native QuickTime codecs. By using QT codecs, it has the compatbility as the regular QT Player. It is compatible with all file types supported by QuickTime - including MOV, MP4, M4V, 3GP, 3G2, DV, AMR, M4A, animated GIF, and FLC animation.
If it can be played in QuickTime Player, it can be played in Windows Media Player, with QuickTime DS Filter installed.
Speed
However, it only uses The Codecs from QuickTime, without the additional weight of the full QT. By using the standard, multi-threaded DirectShow architecture, it is fast and feels at home in Windows Media Player. Indeed, it is often much faster and smoother than the standard QT Player.