BSPlayer can't play MPG but Windows Media Player can???
 

Yes so basically, I have an .mpg file that only has sound and no video when I open it in BSPlayer. When I open it in Windows Media Player however, it plays perfectly. I read in other posts that I have to download an mpeg2 decoder but all of them cost money. Why is it that Windows Media Player, which is free, is able to play mpeg2 files but BSPlayer can't?

BSPlayer is free, but if you remember, you brought mediaplayer with windows (wich is more than 100 $ IIRC), so is not for free.
It has an MPEG2 decoder integrated for DVD playback. BSPlayer can't use it and it needs an external decoder. For more help on MPEG2 decoders, mail me or PM.