I suppose that selling is not necessary, distribution is. Record a movie off cable TV, share with your friends, and lo and behold, they're not going to buy the licensed VHS tape! And maybe even not going to subscribe to cable TV! Losses, losses everywhere.

I remember in 1980, when our school got a VCR and television (on a cart to allow it to be moved from one classroom to another). one of my teachers said that she wasn’t allowed to record something off the air at home and then show it in the classroom.