I thought the same thing at first, but given that his/her (I use this though I believe it is a male) face and chest are covered, I'm not sure what signs of anxiety we would see at that point that are not obscured by the outfit. When s/he looks up at the camera, I think there's a little anxiety there, but that's just MHO. All of the calm walking around, to me, occurred during his/her attempts at staging (like the utterly lackluster attempt to pry open that door). I think s/he was just trying to make marks that looked like a burglary, and there's probably not a lot of anxiety in that particular act of staging.
I wonder, though, what would be point of making sure the murder occurred away from the cameras. Why would s/he be concerned about that, as others have suggested. Surely, s/he knew that LE would figure out how MB was killed anyway. What would seeing it give away?