Hey folks, this comment above mine is what's called a 'straw-man' fallacy. It's when you don't have an argument against for the specific argument being stated, so you invent another similar but significantly different argument to argue against instead. The first comment states that it's ridiculous to ban semi auto firearms when that's the vast majority of guns you can buy, and the second commenter instead argues that they should be legally allowed to own a grenade launcher in sarcasm as an attempt to show how firearm legal restrictions are a good thing as they prevent the ownership of grenade launchers.
Also, it's legal to own a grenade launcher in the US. It's just not legal to own the grenades. Plus, a grenade launcher is really just any 37mm chambered weapon. It could fire grenades, flares, or smoke bombs. They're also single shot weapons, so a semi-auto ban isn't going to cover them.
Hey, I just watched the video on youtube last night. He started off with the good things such as the physical design of the device, or the interesting way it can project a laser image on your hand, but after that, it was all downhill.