Being an attendee from last year, I can guarantee you that it's people still filing in to find seats well into the presentation. The exit is towards the back left of where the camera is. People going to the right are looking for seats. It's still not an attractive angle.
Incredibly annoying! Surely there's another walkway that doesn't pass right through the camera shot!
I understand there are thousands of people there but that particular camera makes it look like a bunch of people are leaving as the speaker speaks.