On video 4 - looks like it is coming off in one corner where I can see a wrinkle in the paper.
But... there is a whole lotta sheet that still looks pretty well adhered. Maybe a couple days in the sun and then a hot bath? Or would the gum start to dissolve?
I've attached paper (Fab EW) to an aluminum cookie sheet with PVA glue.After it's dry, it'll stay on through almost all the steps of normal gum processing. I got this idea from Lukas Werth, who does casein printing, only he uses bone glue pearls dissolved in warm water to attach his paper to glass. It's documented in the Post Factory Journal, issue 6 I believe.