the bug is...
 

after REAL ALTERNATIVE is installed,
your Windows Media Player can play ALL rmvb files.

BUT:
your BSplayer can play ONLY SOME of the rmvb files.

I found the bug.
the bug is: BSplayer chooses the wrong decoders in some cases and the correct ones in other cases.

I hope the BSplayer team can correct this bug soon.

Have you already tried to raise the filter priority of the right codec in BSplayer preferences (CTRL+P -> Filters Management)?
Have you noticed differences?

i have tried without avail.

but now i have solved all the problems
by using the free KMPlayer :)