Former Grey's Anatomy star Kate Walsh steps onto the stage and talks about the worst break-up she ever had. Throughout the monologue, itself a true story, a group of actors behind her start their brains churning, making connections and preparing to riff off of Walsh's anecdote.

When they step forward, Amy Poehler plays a woman exchanging Christmas gifts with her boyfriend. Her gift to him is elaborate, a ten-part opus that at one point includes both a solid gold briefcase and a befuddled Julio Iglesias. In exchange, she receives…

That would be telling, blowing the off-the-cuff punch line to a magnificently improvised scene from the Upright Citizens Brigade. The name probably sounds familiar to you, as the group had a show for three seasons on Comedy Central. What you may not be aware of is that Poehler, Matt Besser, Matt Walsh and Ian Roberts haven't just stayed together while Poehler achieved stardom on Saturday Night Live. They've remained active and become vital to the alternative theater scene in both New York City and Los Angeles, with eponymous theaters on both coasts.

Improvisers and actors drop in and join the Brigade to keep their skills sharp and give them something to do on weekends. We know how dangerous it can be when comedians wander the streets. They all meld together for a show that UCB calls "Asssscat!", and thanks to Shout Factory, you can share an evening of top-notch improvisation without leaving your home.

If you think of improvisation as Whose Line Is It, Anyway?, well, consider that elementary school and this as high school. Based on a format originally called "The Armando Diaz Show" in Chicago, this show takes a celebrity monologist who reminisces based on an audience suggestion. Then a series of scenes blossoms from his or her story. Some connections are obvious; some are not. However, when the troupe is hot, they're all funny.

In addition to the UCB, a variety of guest performers join in, including former SNL regular Horatio Sanz. If you saw Semi-Pro, you might be surprised to see the perfectly tightly wound Andrew Daly explore the dark side of his persona. And man, it's dark.

Again, be warned. This is in no way a family-friendly DVD. While the suggestions might be only borderline offensive - it depends how you feel about medical marijuana, for example - the actors do not censor themselves. Yet they achieve comedic magic. I laughed harder at this - by myself - than I did at the last four or five comedies I've gone to see in a movie theater with an audience recruited by Wild 94.9.

Director Eric Cochran wisely doesn't get too tricky, merely letting the actors go. At least three cameras roam the house (it's filmed at their Los Angeles theater), capturing the action but never intrusively. This is the only captured improv show that is believably improvised.

It's clear that in order to get this perfect moment, they filmed more than one performance. The night featured here has a first act monologued by Thomas Lennon, with the second act by Walsh. In the extras, however, the disc includes snippets of scenes sprouting from stories by Will Arnett, Ed Helms, Paul F. Tompkins and stand-up Jen Kirkman. (Note to Kirkman: Power Rangers are still cool to little kids.)

Even in the show included in its entirety, not everything goes right. Actors occasionally give each other puzzled looks as they try to figure out what the other intended. Occasionally, a line just doesn't make any sense. That's okay, because the next line absolutely kills. In all of it, you see actors thinking, building, creating what Second City historian Jeffrey Sweet once called "something wonderful right away."

It might not matter to you, but you can also see the pleasure they all take in each other's performances. This marks the difference between a good improv show and people cracking up in Saturday Night Live sketches - here, the laughter comes from an actor being outside the scene admiring another's work. This doesn't just come from Besser, Poehler, Roberts and Walsh, though you expect it because of their time together as an ensemble. Poehler in particular clearly loves the form, and loves watching others succeed at it. Yet that never takes away from our enjoyment.

The disc also includes an interview with the core group. They riff, they joke and occasionally, they give the real answer to the question. But it doesn't matter. It's clear that they love to entertain and tell truth in comedy - the title of their mentor Del Close's guide to improvisation.

These guys have managed to be successful in their art, all to varying degrees. But none of them have lost their love of that art. That's rare - and rarer still they've made something so accessible. It's for adults only, but that's okay. Let the kids watch Wayne Brady.

The Upright Citizens Brigade: Asssscat!

Derek McCaw