Thank you all for the kind comments. The falling plate camera is the third I've made. The first one is a large wooden box, 8x8 format, that has a dual sliding pin mechanism on both sides rather than the top. I added some curved metal rods at the bottom, that fit into holes punched in the lower corners of the film plates, like a ring binder notebook, that helps to guide the plates as they fall. I think there's room in this camera for such an upgrade.
The other problem, not mentioned in the video, is what happens to the already fallen plates if the camera gets badly jostled. They could (and do) get upset such that they're no longer flat in the bottom of the camera, and can even block the other plates from falling, or interfere with the pinhole's view.
So when transporting the camera, I try to ensure it stays upright. In this camera, the body of the box is very lightweight while the thick plywood base is heavy, giving it a low center of gravity, which helps.
One other thing that I had to edit out of the video (due to the 15 minute YouTube limit) was the hinged wooden base, which gives the camera a variable tilt angle without the need for a tripod, or with use of a homemade tripod that lacks an adjustable head.
~Joe