The first thing I thought of, like George, was what would happen if the whole thing were to spin with a hand placed inside it. That does not bear thinking of. The bearing looked similar to the ones you get on a lazy susan and as they are an open bearing they clog up very easily.
Chisel choice is a bit dubious although I do sometimes use a spindle gouge the bowl gouge would surely be the best choice. What is wrong with using a live centre and reducing the chucking point to a small cone, switching off the lathe and removing the last little bit which would only be a maximum of 2 or 3 mm across?
The other thing is the bowl in the video is mounted in cole type jaws which should be sufficient to hold the bowl securely anyway negating the need completely for "the gadget".
I do despair at times, people are not taking the time to learn their tradecraft as we did years ago, they want instant gratification for minimum effort and that will only ever give poor results. If the guy demonstrating "the gadget" worked for me I would sack him and whoever hired him in the first place.
