Zack and Miri are a duo, but not a couple. Best buds since elementary school, they share a wry sense of humor and apathetic love résumés. Now 30ish, aimless and platonically sharing a crummy apartment, they work at McJobs that barely keep the utilities paid.

Well, not always. When the water and electricity are shut off for nonpayment, Zack, a shambling teddy bear, convinces skeptical Miri that making a homebrewed adult video would solve their financial problems. When the old friends decide to have on-camera sex, however, new difficulties arise. You know: feelings!

It was just a matter of time until Seth Rogen graduated from Judd Apatow's tender/raunchy romcoms to a Kevin Smith project. Smith, the slacker auteur of "Clerks" and "Chasing Amy," is Apatow's aesthetic kin. They share a dirty-minded humanism, which is exactly the soil Rogen requires for his talent to flower. He radiates an I-dare-you wickedness; his every leer is a troublemaking come-on. As Zack, he doesn't exactly push the boundaries of his abilities. Rather, he's so comfortable and silly and cute that you relax into the idea that he could 1) persuade scrumptious Elizabeth Banks to hook up with him and 2) do it on camera.

Banks (currently doing a note-perfect Laura Bush in Oliver Stone's "W.") makes Miri a great sport and a game gal. When she digests Zack's porno proposition and agrees to help him produce the movie, we suspect that she has some subterranean longings for the big lug.

Pulling together the cast and crew is a comedy of errors. Miri and Zack audition their would-be skin stars with a winning mix of pragmatism and kindness. The "actors," including daredevil Lester (Jason Mewes, the recurring character of loudmouth "Jay" in most of Smith's films) and the exceptionally capable Bubbles (adult film star Traci Lords), become a surrogate family for the couple. Together they guide Zack and Miri through the realization that they're falling in love. Once they overcome the contrived misunderstanding that keeps them apart until the finale, they cease being personal and professional failures and achieve an X-rated version of the American Dream.

It's a pleasant story, but not particularly well-told. It's puzzling that Smith hasn't matured as a filmmaker. Eight films into his career, he's still a scrappy amateur, while his contemporary Paul Thomas Anderson has grown from an indie upstart to a major talent. It's doubtful that Smith will ever make a "Boogie Nights" or "Magnolia" or "There Will Be Blood." At 38, he has just about exhausted the "lovable schlub" act. You leave "Zack and Miri" pleased that the couple have grown up a little, and impatient for Smith to follow suit.

Colin Covert • 612-673-7186