> By the time you got to the upper level classes completely booked 200+ person lecture halls would have less than 50 students show up because everyone watched online.
I don't know whether to blame the professor or the students here--my gut feel is to blame the professor.
I taught at a far less "prestigious" university and that wasn't my experience. I used to record all my CS lectures and practically all my students showed up anyway. And I never took attendance.
Even when I had a "marketing and sales" guy come in to deliver a lecture for me (because, let's be fair--a significant fraction of CS students are going to wind up in non-tech roles so students need exposure to that side, too), practically the whole class showed up. It completely stunned the poor presenter flat who expected that maybe one or two students would show up and instead wound up with a full house.
If good students regularly aren't showing up for lectures, the person delivering the lecture needs to do some serious soul searching and fix the content of the lecture.