The funniest moment in Comedian isn't Jerry Seinfeld telling a joke. It's Seinfeld up on stage at a New York comedy club completely forgetting his monologue, muttering ''Damn it!'' as he paces back and forth, trying in vain to retrieve the bit from his blank brain. To say that it took guts for the famous perfectionist to include this scene in a documentary about him may be a stretch, but Seinfeld, in ''Comedian,'' does reveal himself in small, fascinating ways.
Emerging from his ''retirement,'' he decided to get back to his roots by hammering out an entirely fresh monologue via unannounced appearances at local comedy clubs. We see him anxiously working to memorize his routine in a hotel room, schmoozing with Leno and Cosby, and, mostly, meditating on the Zen alchemy of the Joke. (We also see far too much footage of a decent but rather generic up-and-coming comic named Orny Adams.) The thrust of the movie is that even for Jerry, the quintessential scientist of stand-up, comedy is very, very hard to do. By the end, you're closer to knowing why.