As i.a. mentioned in my Help2Help-post you can determine if you have the proper codecs/filters installed on your PC for a particular movie using (e.g.) GSpot.
Disregard the three "greyed out" submenus of Video-preferences (DivX3, 4 & ffdshow).
With a movie loaded you can check which decoders/filters are loaded by BS.Player (and you can also adjust their settings there) under:
(rightclick >) Options > Filters > Advanced (then click on the [+]-ses).