Here’s a short draft: What the Peeper Saw (1972) — corrupted transmission

In the film, a boy watches his stepmother through a keyhole. That much was real. But the "mtrjm" (maybe "metamorphosis"? "materjam"?) was new: her reflection in the peephole’s brass ring didn’t move when she did.

The file was labeled "fylm_what_the_peeper_saw_1972_mtrjm_awn_layn_fydyw_lfth.mov."