SataniK: If I were in your shoes, I would follow these couple of steps as a rule of thumb...
Fro the purpose of trouble-shooting, make sure you have the elephabt's dream from the
mpegplayer page.
Determine if your installed media player has all necessary codecs.
Give up on that, and download VLC player
here and install.
Try playing it again in VLC.
If it's still messed up, either your computer is too slow to handle conversion, or you need to make sure that either WinFF or the VLC .bat file are configured properly. The link above for mpegplayer has detailed instructions on how to use both VLC and WinFF.
Hope it goes well, fellow traveler.
ComposerDude