If you know someone who has taken an online class or teaches one, you know how much the experience can vary. Some students are very into the class and some are more checked out.
I can't imagine having to teach to a wall of blank screens. You would have no idea if the students are engaged or even listening. Actually, you would have no idea if they were even there.
This professor is obviously loved and appreciated when the students reveal what they're up to. He gets emotional with this realization. There haven't been a lot of surprises in 2020, but this is one of them!