You know he starts out saying it has 6 grams of black powder and I'm thinking that doesn't sound like a lot, so I do some research. The M-80s that we had back in the sixties had just under 3 grams of black powder. Now it is illegal to sell, own, use etc. firecrackers with more than 50 milligrams in the U.S. so I guess 6 grams is a lot.
It reminded me of this one day while I was in high school and this guy had a cherry bomb on the school bus. The fuse had broke off so he touched his cigarette to it to ignite it. It was real loud in the back of the bus but nobody was injured.