The point being that the very first federal gun control law, and the only one to be examined by the Supreme Court, was upheld (if it was, opinions vary) on a false basis. That tape would provide iron clad evidence that: "quot; a shotgun having a barrel of less than eighteen inches in length" at this time has some reasonable relationship to the preservation or efficiency of a well regulated militia" Maybe we need to get an NFA case started on its way to the SC based on a violation of the short barreled shotgun portion of the law. I'm sure the Gunny would be happy to supply the video. :)
Of course a machine gun case would serve as well, plenty of evidence about that can be obtained from most any combat video shot during the ongoing unpleasantness in southwest Asia.