So you need to play a video file that you have been given and are experiencing problems with Windows Media , Quicktime etc.
Try Videolan with the VLC Media Player which can play "most audio and video formats (MPEG-2, MPEG-4, H.264, DivX, MPEG-1, mp3, ogg, aac ...) as well as DVDs, Audio CDs VCDs, and various streaming protocols. "