Why did the VCR have to be on channel 3 to record back in the day?

Old people remember that you had to have the VCR on a certain channel (3 or 4) to record programs off of the TV in the 80s/90s.

This clip from the Movielife Crisis podcast covers exactly why that is. For the full episode, go to http://www.movielifecrisis.com, this comes from our City Slickers episode.