VLC media player will play em (will on my machine), will play most formats and has other options,
http://www.videolan.org/vlc/ a free programme
or you can download using keepvid as MP4 should be better quality but possibly more difficult to find a player, tho VLC again......
Media Player Classic, also hits most formats
http://www.free-codecs.com/download/...er_Classic.htm