Laugh, I nearly did!
This is "Sandpaper vs. Ways Ultimate Solution" in my workshop, the concertina bellows overhangs the ways by 2" front and rear and can be brushed and vacuumed clean after dirty jobs whilst the ways stay perfectly clean and liberally oiled.
I use a variety of milling and grinding units on the lathe and the bellows catches all the debris. the front clips in place, the rear is held by one screw, that's "Sandpaper vs. Ways Ultimate Solution"
Maybe I'm new to all this but didn't he just destroy the bearing he was going to use by having all the grit fall down into it while he was sanding?? I mean it's not even a sealed bearing. I certainly wouldn't want to put that thing into an engine afterwards - especially since it is holding the crankshaft.