Her behavior in the elevator video has always struck me as rather playful. The way she leans way over, with her feet at the edge of the elevator and her back almost parallel to the floor, her head poking way into the hall--that seems like such a playful move. It's silly, not stealthy. She does look like she's hiding from someone, but not someone she is afraid of. It looks more like hide and seek. When she stands in the elevator, she assumes an attitude of alert waiting, facing the door, as though preparing to surprise someone. Even when she moves into the corner, she still has that look. When she steps out of the elevator and gestures wildly, I'd guess that she's trying to communicate with someone down the hall--someone else playing the game. Perhaps the other person is also trying to hide, and she's telling them to get down out of sight. Or maybe she's describing how she's frustrated that the elevator doors won't close.
I've always wondered why it takes the elevator doors 3 minutes to close.