I don't think we know for sure that is where MB disappeared but I guess we can now assume that as we know (kind of) where she ended up.
I'm trying to think how SP got back to the north hallway. Did he walk through the auditorium (beginning at the last video where it appears he is going to attempt entry into the auditorium at the sw entry) to one of the exits on the north side of the inside of the auditorium. If he wasn't picked up coming out of the auditorium door closest to the NE camera, chances are he came out of the auditorium at the door closest to the NW corner. In this
scenario, he possibly could have been oblivious to headlights and MB making entry and was caught by surprise or he heard her and got his gun out.
Do burglars carry guns? That's a huge leap from "roaming halls" to murder.
IMO, this whole thing appears to be full of incredible coincidences as well as extreme luck. Unless, of course, SP knew all of the camera outages.
@Gumshoe Stories, I may be imagining this but I recall in the early release of the videos, SP was seen walking away from the busted doors. For whatever reason, police took that part of the video out. That image would have been from a NW camera so maybe I'm not recalling correctly.