I even have a VHS VCR that does this automatically. It’s fascinating - once the recording is done it rewinds and watches the show at high speed, when it sees so

I even have a VHS VCR that does this automatically. It’s fascinating - once the recording is done it rewinds and watches the show at high speed, when it sees something in the signal that indicates that an ad was spliced in it marks the start and end. Then when playing back it fast-forwards over the commercials. It worked brilliantly, back in the days of analog cable TV.