I took a closer look...
I don’t have a DVR....I usethe youtube controls.
there are more people in the video than in the still.
The people in the still are in the video.
I watched the video a few times and I can’t tell if the background is in a loop.
So strange. Why would they even put people behind her? Don’t recall other responses to the SOTU that had an “audience” on set. (But, I admit, I have not actually investigated the subject.)