1. maybe update your bsplayer. last version is 0.86.501 (16 sept) and ogm support has been getting better and better I think (I don't have that many ogm files)
2. feed your file to
Gspot. It will tell you what you need to play your file and whether your system is currently able to play it correctly.
If you miss a video codec, I'd suggest ffdshow (latest alpha version on
sourceforge) which acts as a replacement for several video codecs (as a decoder only)