answer: just a man . no one else .
question: how may people are in the video ?
answer: we see him walking down the stairs from the floor above .
question: is he present at the beginning or did he walk in ?
answer: it is just a stairwell . we dont see the rest of the room .
question: what sort of room is he in ?
answer: when he reaches the bottom of the first set of stairs he looks around and then grabs a rag and wipes the window .
question: what is that he is touching ? is it a window ?