ffdshow can be found on sourceforge:
http://sourceforge.net/projects/ffdshow/
select ffdshow-alpha.
oh, and it might be that a filter that flips your movies back in place is loaded by other players but not by bsplayer: there are a few filters that are loaded only if bsplayer is using overlay mode 2 instead of mode 1 (look in bsplayer preferences, video tab)