Here is a cool video inside Chinese firecracker and fuse factories. The video is a bit slow and could easily be edited down to half of the 40 minute length without losing any content, but is still very interesting. It is fascinating to see how much work is done by hand, and almost hard to believe they can make enough firecrackers in this way to meet demand. The firecrackers in this video seem to be for domestic Chinese use, which makes me wonder if there is a different (perhaps more technologically advanced) way of making the kind we see in the US. They don't measure the flash powder, and it looks like a lot more than 50mg, so perhaps the stuff we get is made some other way. I wish there were some interviews with people from the factory instead of just the narrator, but it is still very interesting.
Firecracker and Fuse Manufacturing in China (Documentary)