Just a guess here - do you have any toolbars on the right-hand side of your screen? Or is your taskbar docked there? A similar issue was discussed here:
http://forum.bsplayer.org/viewtopic.php?t=3523. It was found to be that BSPlayer will mess up the video unless your taskbar/toolbars are at the bottom of the screen. Any other location causes strange junk to appear on the opposite side of the video.
Let us know if this is or is not the same issue you have! :D