Did you try color controls (increase contrast)?
(rightclick >) Video > Color Controls
What (video-)filter/codec does BS.Player use for playback of this file?
(rightclick >) Options > Filters > Advanced
(clicking on the [+]-signs reveals further info and access.)
If e.g. ffdshow Video Decoder, try playing with luminance offset or gain:
(rightclick >) Options > Preferences > Video > FFDshow properties
If e.g. DivX-codec is used for decoding (I still have good old version 5.2.1 installed) you can also change brightness/contrast in its properties ('Quality settings'?) provided Yuv Extended Mode isn't used. (Note you can access filters/codecs through Filters > Advanced etc.)
Ditto for other decoders (like e.g. Xvid)
P.S.:
The video rendering mode used may also of interest.
Maybe also read
this info.
(Thread moved to more appropriate forum.)