I thought it was Greyback too! Wasn't until I tried to find the actor that I realized it wasn't. In the books it's Greyback who pervs on Hermione; maybe the bestiality aspect of that was too much so they gave that to the hot human instead of the werewolf.

Yeah, all the later movies seem to be fond of really low lighting. How we gonna like the movie if we can't see it, huh directors?