My post most likely won't add anything new either, but then again, at least it continues the discussion of this case (which has dried out recently), so here's my two cents:
I do not think she is drunk or under any type of drugs when she gets on the elevator. I could understand why some would think that, since her behavior is odd, but I disagree with that sentiment. To put it quite simply, people do weird things when they're alone sometimes. When I think about it, I can remember specific examples of when I felt I was alone, that I've done things similar (pretended I was being followed, talking to myself, etc). It's a very child-like quality, but one a 20-something still very much can possess. It's almost like she's "celebrating" (for lack of a better word), subconsciously, her freedom of being all alone on the floor of a hotel (which can be as desolate and abandoned as any hotel I've ever stayed at, 5 star or 1 star) playing games with herself. There is no panic that I can sense.
After she peers out to the left and right, when she jumps out of the elevator, I can imagine her yelling "HA!" There's nobody there, and she's not surprised by this -- because she never truly believed her life was in danger. Perhaps she was entertaining the thought of someone trying to get on the elevator from outside, which would've been why it wasn't moving. This is dispelled quickly after she jumps out.
When she re-enters the elevator, she's laughing at herself -- because she knows what she's doing is goofy. She puts her hands to her head, saying to herself, "am I crazy?" because she knows nobody is (nor was) following her.
The bending of her fingers on her hands, to me, is her counting the seconds it's taking for the elevator to get going. She has no idea she's pushed the hold button, so she's utterly confused as to why it isn't moving. I see frustration, in both the way she's bending her fingers and the slight buckling of her knees. The game she's playing with herself isn't funny anymore, and she's become slightly annoyed now at her predicament.
At the end, she simply wanders off on her own volition. I still wonder if she was close enough to hear the elevator doors close; if she returned after they closed. Part of me thinks she didn't -- she took the stairs, perhaps thinking she could get on the elevator on another floor (she wouldn't want to walk all the way down to the 4th floor).
In the end, I don't think this video has any direct correlation with her death. It's absolutely haunting, in every sense I can think of, but nothing substantive can be obtained in determining how she died ultimately. If anything, it illustrates her state of mind, and gives us somewhat of a timetable from which to work; so it is somewhat useful.
