This one is a candidate for the Darwin Awards!, or at least a lesson on how NOT to do something! Clamps can work, but you need the correct clamps and a correct clamping surface.
At least he had the good sense to videotape it for our entertainment.
A lot of people have no idea how much power and thrust even modest engines put out. I have seen stuff like this time after time. I sold an engine to a guy for R/C one time. Nothing particularly macho - an HB 40 PDP. He wants help starting it, so I go over to the house, and he has a Dave Brown mount - OK - screwed to the grain end of a 2x4 with #4 wood screws that go in about 1/2", clamped to a card table in his garage. I talk him out of the card table and do something better for the engine mount, and clamp it with 2 c-clamps to his workbench. I warned him, "hey, all that stuff hanging up it going to get blown around", but we proceed. Start it up, not too bad at idle, he pushes the throttle to full, and it immediately blows all the stuff off the pegboard, and the card table gets picked up and and thrown up against the back wall of the garage.
Another one, my dad modifies his old McCoy 29 to have a *much larger* venturi, like 3x as big. He mounts it on something, clamps it to the picnic table, fires it up with a Top Flite 10-3 1/2 nylon. He gets it started, and sets it at a medium 2, really cranking, and then we stand back and let it run. As the fuel runs down, it gets leaner and leaner and faster and faster, he's very pleased - and then the picnic table starts scooting across the patio, hits a joint in the concrete, and flips over.
So, many people have no real appreciation of the kind of power or air blast you can get with these things, and I have seen stuff roughly equivalent to that video many times.
Brett
p.s. The McCoy 29 was intended for a Top Flite Superform P-47 kit with about a 2-foot winspan, for me *at ~9 years old*, to fly. We built the airplane, put the old McCoy 29 in it, and I get sent out to fly it. About 15 seconds into the flight, I start panicking because I can't possibly hold on to this heavy beast at Warp 7, and in my mind, invent the safety thong. I start screaming for him to come get it, but fortunately it quits.