I’m pretty sure the editors for a “MovieBrainz” would be there, but it would require somewhere for them to do their edits. One of the reasons BB isn’t seeing much activity right now (even if it is seeing some!), is that BB is still very(!!) rough around the edges and doesn’t lend itself to a very smooth editing experience. MB certainly also has some rough edges, but it is still possible to do more things more smoothly than what is currently possible with BB. Hopefully BB will eventually trump MB’s editing experience, having learned from MB’s shortcomings, but it is not quite there yet. Maybe if you start a MoB (VideoBrainz? FilmBrainz? There’s probably a better word than “Movie” that would encompass TV series, possibly music videos, and possibly YouTube/Vimeo/Facebook/… videos), other people will join up. I can’t remember who originally started BB (@LordSputnik, maybe?), at one point it was led by @ocharles, and now it has a dual lead in @LordSputnik and @LeftmostCat. But someone needs to actually do the initial spark before a fire can catch on.