The thin, secondary lid for the pan is an old idea too. It was used as a safety, similar to a snaphaunce, so the frizzen could be out of the way and still keep the priming covered. There was a small catch so when you closed the frizzen it hooked onto the thin cover and made it act as one piece when you pulled the trigger.
Not to detract from a very nice, innovative piece of work. The guy has talent.