[Wistar]

In the early 80's, I modified a VHS cassette by placing a cylindrical high-strength magnet adjacent to the tape path on the takeup side. There was a nearly perfect pre-existing pocket in the case webbing to put the magnet with a dot of glue. The idea was to make a play-once, self-erasing cassette. Although not perfect, it was effective enough to really screw up the second playback. Probably screwed up the tape deck, too, but I don't recall any real evidence of that.

[washadjeffmad]

That was a common "self destruct" mechanism for VHSes issued by courts and other legal agencies for sharing decisions and reviewing certain evidence.

One of the VHS archiving communities I'm in found one in a sealed envelope at an estate sale, played it, and then started a thread describing the content and asking if anyone knew why they couldn't get it to play a second time.

[Wistar]

I played with the idea as one way to deal with a problem client. At the time I had never heard of the method.