That's not the only reason. I am not expert by any stretch, but I believe video codecs work by essentially storing diffs of different frames rather then the ent

That's not the only reason. I am not expert by any stretch, but I believe video codecs work by essentially storing diffs of different frames rather then the entire frame. I imagine in a programming class, a large portion of the screen will not need to be redrawn very frequently (background of slides, things on the wall of a classroom, etc.). However a fast moving FPS will constantly need to redraw almost everything in the environment. So that would necessarily require a lot more throughput per frame.