If she were to faint or fall, no one would see it because the audience is elsewhere. She cannot afford to risk such an embarrassing moment this close to the election.
There is something not “right” with this video, looking at the still picture and matching it to the video shows the audience quite a ways behind her. There are also people between her and the audience on stage. I don’t think it is a “depth of field” issue, but I agree, the sign on the podium doesn’t look quite right.