Didn’t watch the video- I wish there were pics. Sounds about like the steam-powered machine gun the Mythbusters built.
This guy’s a member of the slingshot forum, as I am, and has built some interesting stuff. One is a semi auto slingshot that shoots bolts made from large nails.
Watched most of it, didn’t see an impact though just the shot being flung out. I want to see the super large one with a shot put for ammo.
Isn’t this hard to aim? Wouldn’t it be easier to build a drill-wound crossbow with superhuman draw weights?