Maybe you should first try different settings on the video-tab of "Options/Preferences" (with respect to overlay and/or RGB); have a look at this post:
http://forum.bsplayer.org/viewtopic.php?p=3169#3169
If that does not bring you the solution, there is another possibility in the latest builds, in which connection please see this post:
http://forum.bsplayer.org/viewtopic.php?p=6308#6308