When I found Chicago filmmaker David Thomas last Thursday, he was planted in front of a computer at the River West video editing house where for four days he’d been trying to cut 14 minutes from his first feature-length movie, MC5: A True Testimonial. He’d eliminated 10 minutes of footage so far, and was struggling mightily to find the last few disposable moments. “It’s pretty slam-bam all the way through,” he explained. “We’re at the point where we’ve had to take out parts of the story. We lost a whole character yesterday.”

Still, he was in good spirits: after nearly seven years the movie, which documents the rise and fall of legendary Detroit proto-punks the MC5, makes its world premiere as the opening event of the Chicago Underground Film Festival this week. Thomas, his wife, Laurel Legler, and Jeff Economy partnered up to start the project in 1995, expecting to complete it by 1998. But by 1999 Thomas and Legler were still shooting interviews and collecting archival material, and Economy had backed out. “I don’t doubt that they’re absolutely sincere about making this film,” he said in this column that year, “but I don’t want one work to be my life’s work. I don’t want to be defined by what some other people did almost before I was born.”

Thomas and Legler had no such qualms. “We didn’t do this to further our film career. We did it because it was the MC5,” says Thomas. Quoting Brother JC Crawford’s incendiary intro to the band’s signature recording of “Kick Out the Jams,” he adds, “It’s our purpose here on the planet.”

Thomas admits he’s had his doubts along the way: “I remember an incident in a Tucson hotel room,” he says. “I had the whole crew there and I was like a raving lunatic–‘I don’t know what we’re doing here, I don’t know what I’m doing, there’s no fucking story. What have we been doing for the last three years?’ It was like Hearts of Darkness.” But the couple say their enthusiasm for the subject matter sustained them–and even as they showed me a brief clip in the editing room, they began bobbing their heads to a tune they must’ve heard a thousand times in the past few years.

In April the pair finally screened a 135-minute director’s cut for friends, family, crew members, and the subjects. (I haven’t seen it; there’ve been no press screenings.) It hasn’t been picked up by a distributor yet, but it has been accepted by the prestigious Toronto International Film Festival, which takes place in September, and it is at the programmers’ request that it has been shortened. Thomas and Legler had already expected to have to edit it down for distribution, so they weren’t too upset. “It all comes down to art versus the restrictions of the marketplace,” says Legler. “We always said that we didn’t work on this film so that no one would see it.”

To that end, Thomas and Legler have also signed on with Cinetic Media, a New York consulting firm that, among other things, secures distribution for independent films. Cinetic head John Sloss, a veteran entertainment lawyer, has served as executive producer for scores of good small films, including works by Richard Linklater and John Sayles.

MC5: A True Testimonial is showing at 7:00 and 10:30 PM on Thursday, August 22, at Landmark’s Century Centre, 2828 N. Clark. It’ll be preceded by a trailer for The Monks: The Transatlantic Feedback, a documentary about garage-rock cult heroes the Monks. Advance tickets for all CUFF screenings are available through Ticketweb, www.ticket web.com or 800-486-3401.

This year’s CUFF lineup features numerous other films about music. The best of those I’ve seen is Joey Garfield’s Breath Control: The History of the Human Beat Box. Beatboxing is the sparsely practiced hip-hop discipline of vocally mimicking drum machines and turntable scratching; this lively, informative, well-paced documentary assumes little knowledge on the part of the viewer, but it doesn’t come across as pedantic either. Tracing the form’s development from early practitioners like Darren “Buff” Robinson of the Fat Boys and Doug E. Fresh through current stars like Rahzel and Scratch, it contextualizes beatboxing amid old African vocal traditions and jazz scat singing and even examines its global cousins. (Marie Daulne of the Franco-African group Zap Mama demonstrates international variations and smartly analyzes the differences.) There are loads of interviews with hip-hop heavies, including DJ Premier, Bobbito, and Biz Markie, and some priceless archival material–including a clip of Buff doing his thing with Regis Philbin on the Today show in 1984. Breath Control is showing Sunday, August 25, at 7:00 PM and Tuesday, August 27, at 8:45 PM at Landmark’s Century Centre.

Another of CUFF’s music-related offerings, Our Nation: A Korean Punk Rock Community, tackles a fascinating topic: the mid-90s emergence of punk rock in Seoul. Though the scene isn’t by any means cohesive or easy to pin down–the subjects argue over a definition of punk and disagree about what their activities really mean–over the course of the 39-minute video a sense of developing community does come through. Directors Timothy Tangherlini and Stephen Epstein make some odd aesthetic choices, though: an extended segment on the all-female band Supermarket lets the drummer yammer on about how much she enjoys doing laundry, and for a full minute we watch her clean a pair of socks. Sooyoung Park, the Korean-American musician who fronted the Chicago indie-rock band Seam, narrates. It’s showing Friday, August 23, at 6:45 PM and Monday, August 26, at 1:45 PM at Landmark’s Century Centre, on a program with the animated short Rude Roll (How to Dance Ska) and Useless, a documentary about Gerry Hannah, the former Subhumans bassist who went on to become an infamous Canadian terrorist.

Amsterdam’s the Ex are one of the most interesting rock bands of the past two decades, and I was excited at the prospect of a documentary that might trace their transformation from chaotic anarchist punks to brilliant intuitive improvisers. Unfortunately Beautiful Frenzy, a ploddingly amateurish video documentary by Swedish filmmakers Christina Hallstrom and Mandra Waback, is a jumble of talking heads (including Chicagoans Steve Albini and John Corbett) and poorly shot, poorly recorded performance footage; there’s little exposition of the creative process and there often seems to be no narrative thread. It’s showing Tuesday, August 27, at 5:15 PM and Wednesday, August 28, at 1:45 PM at Landmark’s Century Centre, preceded by Armor of God, a short video about the Clang Quartet, a one-man band from North Carolina.