“Thank You, Del” exalts the continuing legacy of Del Close, the late actor, writer and teacher whose coaching of numerous future stars (including multiple “Saturday Night Live” generations) and popularizing of improv techniques indelibly shaped modern comedy. Todd Bieber’s documentary doesn’t offer in-depth biographical treatment, or even much insight into improvisation itself, preferring instead to dwell on some celebrity personal reminiscences and the torch-carrying annual Del Close Marathon hosted by acolytes the Upright Citizens Brigade. The result isn’t all that enlightening, but provides a fun watch with comedy luminaries like Amy Poehler and as-yet-unknown talents demonstrating their love for the performance idiom on stage and off. Cable broadcast is the pic’s natural destination.

Close, who died in 1999 at age 64, worked in various New York stage settings (including with Mike Nichols and Elaine May) before joining San Francisco’s influential sketch comedy troupe the Committee in the late 1960s. Returning to his primary base in Chicago a few years later, he spent a decade as Second City’s resident director before being let go for reasons related to the substance abuse that fueled what one colleague calls his “self-destructive nature.” He then started his own theater, ImprovOlympic, with Charna Halparn.

In all these capacities he played a huge role in honing the skills of a dizzying talent array, from Bill Murray (who threw a party for Close on his deathbed) and other original “SNL” cast members to Jon Favreau, Tina Fey, Mike Myers, Shelly Long, Bob Odenkirk, Dave Thomas, John Candy and many more.

He could be a harshly critical (but unusually constructive) instructor, and a trainwreck in his general no-impulse-control behavior. But apart from a few choice anecdotes, he remains largely an enigma here — perhaps fodder for a separate documentary.

More disappointingly, “Thank You, Del” only glancingly references the history of improvisational theater before him (it began in the 1920s as a form of therapy for problem children), and doesn’t really define Close’s specific contributions. We never learn exactly what “Harold” (a blueprint improv form he invented) is, and get just drive-by samples of other formats like “Gravid Waters” (when one performer speaks lines from an existing play and another improvises in response). One thing that does come across clearly is how important he was in legitimizing improv as more than just a party trick or developmental means to an end (like a finished play), establishing it as the widely popular entertainment and art form it is today.

Most of “Thank You, Del” focuses on the present rather than the past, as it chronicles the 2014 edition of the Del Close Marathon. In its 15th year, we see the event encompassing numerous New York venues, drawing performers from places as far-flung as Finland, Portugal and Japan over a weekend’s nonstop course. One visiting group stuck with a wee-hours slot is Hi Let’s Be Friends, a very green quintet from small-town Missouri whose experience Bieber follows. (It’s not just their first Big Apple trip; it’s the first time they’ve even seen improv performed live by anyone but themselves.)

The other principal figures here are the core members of Upright Citizens Brigade — Poehler, Matt Besser, Matt Walsh and Ian Roberts — whom Close saw as his particular torch carriers. While the comedy we glimpse over the weekend is highly variable, these inspired pros inevitably raise the bar whenever they step in, climaxing the pic with a very funny riff on Isadora Duncan’s unique death.

Though not particularly stylish, the production is well paced and pro in all tech departments.

SXSW Film Review: ‘Thank You, Del: The Story of the Del Close Marathon’

Reviewed online, San Francisco, March 10, 2016. (In SXSW Film Festival — Documentary Spotlight.) Running time: <b>84 MIN.</b>

  • Production: (Documentary) An Upright Citizens Brigade Comedy presentation of a Don't Think Prods. production. Produced by Julie Gomez. Executive producers, Matt Besser, Matt Walsh, Lauren Kahn, Juliana Brafa, Denis Cardineau, Moujan Zolfaghari, Dave Szarejko, Justin Byrne, Matt J. Weir.
  • Crew: Directed by Todd Bieber. Camera (color, HD), Denis Cardineau; editors, Cardineau, Tessa Greenberg, Zach Goldbaum; music, Matt Rubano, Jamie Siegel, Nathan Kil; sound, Peter Yelton, Nic Stanich; re-recording mixer, Allison Casey.
  • With: Amy Poehler, Matt Walsh, Ian Roberts, Matt Besser, Adam McKay, Horatio Sanz, Nick Kroll, Jim Santageli, Tina Fey, D'Arcy Carden, Keisha Zollar, Andy Rocco, Team Finland Improv Troupe, Hi Let's Be Friends, Doppelganger, Michael Cera, Louis C.K., Mike Birbiglia, Charna Halparn, Alan Myerson, Howard Hesseman.
  • Music By: