I hope this kid blows himself up.
*hem hem*
About weapons.
To be honest, the inherent problem with weapons and especially this flamethrower is that their main intent is to kill. That is what the item is built with the intent for use and why one is purchased. Now, you might intend to kill in self-defence, or only kill animals, but the idea is still that it kills things, and what it kills is up to the user. That is the intent of weapons.
Now, a car for example, could kill. But that is not the intent of the item. Designers often keep in mind ways to lessen its' ability to kill, like seat belts and air-bags, and special breaks and the like. Cars have uses and are intended for use for things, not killing.
Anyways, this is rather "Stupid", this item, if it was made for any other purpose then a mental exercise. If someone made a flamethrower for any use a flamethrower was intended for (Killing) then obviously its' a danger. I don't see why you'd make it for anything it wasn't intended for, as there would certainly be a better tool and you are putting people at unnessecary risk. If it was made just to see if such an item could indeed be made, then perhaps, but the person should have been more prepared to make people aware of the dangers of making an item that uses flame.