You can save this as a reg file and merge it to registry.
(I only use BSplayer for AVI, MPEG and MPG so it may be a bit incomplete for you)
Code:
Windows Registry Editor Version 5.00
[-HKEY_CLASSES_ROOT\Applications\bsplayer.exe\shell\Open]
[-HKEY_CLASSES_ROOT\Applications\bsplayer.exe\shell\Play]
[-HKEY_CLASSES_ROOT\BSPlayerFile.AVI\shell\Open]
[-HKEY_CLASSES_ROOT\BSPlayerFile.AVI\shell\Play]
[-HKEY_CLASSES_ROOT\BSPlayerFile.MPEG\shell\Open]
[-HKEY_CLASSES_ROOT\BSPlayerFile.MPEG\shell\Play]
[-HKEY_CLASSES_ROOT\BSPlayerFile.MPG\shell\Open]
[-HKEY_CLASSES_ROOT\BSPlayerFile.MPG\shell\Play]
It removed the 2 items for me and stays removed after restart.
Unless you register the file type to BSplayer again, it shouldn't come back.