In St. Louis in the early 80's one of the independent tv stations (KDNL channel 30) had over the air pay movies. I think it was called Preview and they scrambled the broadcast signal and you had to rent a descrambler. It started at 7pm every night. They would often leave it unscrambled for the first few minutes of a movie, I think intentionally as a teaser.

The idea was there were so many rural areas around here that didn't have cable that there would be a market for it. It apparently didn't work as planned because it only lasted 2-3 years. I'm sure the stations ratings fell through the floor.

Our town got cable in '82. I remember several channels became something else at night. I know Nickelodeon was one of them. I don't know if that was the local cable that did that or if it was national.