Guess I've just gotten old....sorry, Raven.
No need to be sorry, Doc. You're not old, brother. You're just not as sadistic as I am, that's all. 
Like I said I did sh!t like that as a kid. Honestly I wasn't even smart enough to attach a hose to keep the flames from backing up into the can. At least the kid did that so technically he was a lot safer here then when I did it with just a can and a lighter. From all the times I did it I most likely just got lucky I didn't end up blowing my hand off. Then again I used to light M80's and then shoot them with my sling shot before they exploded. If I wouldn't have been as fast as I was I would have blown my own fingers off.
The water jet-pack, as you can see in the vid, is dragging a small boat shaped object that is attached to the hose. I think this keeps the jet-pack weighted down and tethered so the hose can't come out of the water. As you point out though, all this thing has to do is hit a large wave that takes the boat end out of the water for a second and the pilot would slam into the water/boat/ground.....ouch...LoL.
Wow, that jet-pack looks like a ton of fun! I would definitely like to try that out sometime.
As for the flamethrower...........I guess we have to give the kid credit for not injuring himself, but personally, I don't think that's much of a good idea. If anything, it's just providing motivation for other kids to attempt (more) dangerous things. Playing with fireworks is one thing..........but this takes that to a whole new level..... Great videos for a Monday morning though, thanks Raven
Don't mention it, man. 
