I'm convinced that there is someone to her left. The reason is that at around 1:25 in the video, if you watch the bottom of her skirt/shorts, it goes down about an inch or so. At first I did not see that but close watching shows this happening.
The position of her hands behind her head makes it unlikely that she tugs her skorts down. Both hands seem to be behind her head. We know she never lowers her right hand because that elbow is in view. It is not likely she lowers the other hand either, because of the position of her arms when she enters the elevator. Therefore, there is someone there who tugs her skirt/shorts down slightly.
I interpret this as someone reaching into her pocket, perhaps looking for her room key, which he may obtain. Her room key is probably in her pocket since we never see it in her hand and she is not carrying anything.
I can't remember seeing much discussion on why/how her shorts go down in this way. I see it a clue that there is probably someone there. My opinion, but I'm reasonably certain of this one.
IMO, I always thought there was someone on the left of the elevator.
Her odd gestures while standing on the left of the elevator was due to her being frisked or groped by a person.
I didn't notice her shorts moved down a bit while her arms were up until you pointed it out.
It does look to me her pants did come down couple inches.
IMO, after she stepped back in the elevator from dashing out to check the hallway, the person at the left may have appeared. Since she could see the person from the mirror from where she stood, she moved to the corner in order to stay out of the view of the person.
At first the person may have questioned her for being there during that time of the night. Later, she was ordered to step out of the elevator and move closer to him, all along the person deliberately stayed out of the lens of the CCTV. (Her playful attitude in hopping out and so was probably at the moment she still didnt feel any serious threat.)
IMO, she was being asked to put her hands on her head, she probably explained to the person why she was there and the person frisked her and let her leave.
However the person may have changed his mind and kept the elevator door opened by pressing the button.
The elevator door wouldnt close, she was being asked to step out from the elevator again.
At this point the person frisked her again and groped her, he may have asked her if she took anything or where is her cell phone, that is why she did the open handed gesture. (She turned her body to avoid the person but was talking and explaining to him at the same time.)
After that the person started to grope her more. That is why she had those counting fingers and knee bending gestures.
She was later being lead or pulled away.
Of course this is only my speculation.