fum

I have a very similar memory but can't for the life of me remember anything else about the movie!

For a while I was convinced it was A.I. Artificial Intelligence the scene had Jude Law's character Gigolo Joe in it. But from a quick search that doesn't seem right.

Apparently it's a trapetum

https://en.m.wikipedia.org/wiki/Millstone#The_Roman_trapetum