MPlayer

MPlayer is a multimedia player that has support for Win32 codecs, UniAud, DIVE, SNAP video overlays, and WarpOverlay. There is a browser plugin included, as well as MEncoder, a simple movie encoder. Most MPEG/VOB, AVI, Ogg/OGM, VIVO, ASF/WMA/WMV, QT/MOV/MP4, RealMedia, Matroska, NUT, NuppelVideo, FLI, YUV4MPEG, WebM, and more are supported.