I don't have any bspfilters.dat, Vobsub works without this too.
I've uninstalled Vobsub, removed both Gabest entries from registry...I can't make it fail to work.
But I'm not playing from CD, I do from HD. And my movies are DivX+mp3, not xvid+ogg or even ac3.
To manually unregister vobsub filter, you need to put the dll in the same direectory.
I would be curious curious to learn how many vobsub occurence you get in the movie properties with such a bspfilters.dat, as all of them stand in the "force auto load area"