That is a camera, and I guess he just bought one with a tripod mount in it. Are you sure there isn't one on yours with a rubber plug in it so you can't see it or something? Most cameras come with a female threaded socket for tripod.
There were two different purposes for the chemicals in the guns, one is of course propulsion of a projectile, and the other is incendiary effect. Tne asa...? must be a part of the incendiary mix, as I would think is the special varnish. There was other stuff they put in too, such as zinc. Originally mercury was prescribed, but due to environmental issues zinc was substituted. The measuring and mixing operation for just one load lasted I think over a half hour, and since you-tube limits the whole video to 10 minutes, there's a lot left on the virtual cutting room floor.