bad idea for an experiment:

take a betamax tape, and a vhs tape. open both casettes, remove the actual tape, and put the beta tape into the VHS cassette.

First of all, it won't play. obviously.
but then see if we can record to it and play it back.

dooo dooo doo dooo....
I'm in. (to the Beta tape)
and I'm into the VHS tape
cross-winding the tape
where's a VHS rewinder when you need one?

why VHS beat Beta in one, oversimplified example:

The reel on the right is beta. the reel on the left is VHS. A bigger reel meets it holds more tape. More tape means it can record for more minutes.

@foone that’s a big old spool!