The mark of an excellent documentary is transcendence over its subject. You think you're watching a film about a whole element of professional musical theater, industrial musicals, that very few people have ever heard of. But after a bit you realize it's also about this guy, a comedy writer who isn't sure if he's funny anymore, who doesn't think he's got a second act in him, who finds himself out of work right before he turns 50 and ends up writing his own second act. This is a fantastic film about composers and librettists, performers and collectors, but it's also about getting old in America, about the scorn we level towards artists when they make money, and about how bleak your personal outlook can be when you don't think you have time to reinvent yourself.
It's also got Jello Biafra in a Broadway-style musical number, holding an armload of toilet plungers.