You need to look at the extension and see what the file type is.
Chances are it's a .RM file, since we do not provide support for them and people have to put them in a .ZIP file to upload them. If that's the case, you need a player like Real Player from
http://www.real.com/
Or it may be an .MP4 file which can be played with
Quicktime Player.
Good luck,