The film being that close to the edge of the platter gives me MASSIVE anxiety. I've dealt with brain wraps or film melting in the gate, but those are easy compared to film slinkying off the edge of the platter. Nothing like coming into a booth to find hundreds of feet of film in a rats nest of sadness and rainchecks.
I was watching this video on IMAX film and noticed that the outside film is actually fixed in place and the reel unspools from the center and fills up the reel on the other rack. So fortunately it isn't possible for it to unspools from the outside. https://youtu.be/gENOhw1Q3vM
Correct. That's how most 35mm projectors work as well. The film feeds out from the middle of one platter, through the projector then onto a return platter where it spools from the center out. But if the tail of the film (which is on the outer edge) comes loose and falls off the edge it could cause the entire print to spin off the edge of the platter, one layer at a time. It's like a slinky, the weight of the film falling will make it fall faster and faster. It would end up in a big circular pile that would be an absolute nightmare to get back on the platter.
There's nothing worse than coming into the booth and finding hundreds of feet of film tangled on the ground.
Thank you for taking a few moments to learn about it yourself! The link you provided to the Imax video wasn't one I'd seen before, and I love watching that kind of shit.