This may just send you off on a wild goose chase.......but I have found this site helpfull :
http://www.videohelp.com/
Do a search, I found a few references, some suggestions are just change the .mod extender to .mpg, I know that you can do this with other video files but may lose something ?
Other suggestion was that the latest windows player may play them, there may also be audio codecs involved, good luck.