Most probably a codecs/filters question.
Did you - at installation - allow BS.Player to install codecs/filters locally (i.e. for BS.Player's own 'internal' use only, so not interfering with others)?
If not, you can still do this by going to BS.Player's installation folder and running "bspcodecdl.exe" from there.
(
LIST OF CODECS (optional if BS.Player Codec Manager is used))