Before you see the new Colin Firth movie Arthur Newman in theaters on April 26, you can watch it open on BitTorrent. You can do that with pretty much any movie these days; the peer-to-peer file-sharing protocol has more than 170 million members who collectively offer up a bottomless well of pirated media. But for this movie about a former professional golfer and FedEx (FDX) employee who assumes a new identity after faking his death, the digital offering is actually part of the official marketing roll-out.

Los Angeles-based film distributor Cinedigm has partnered with BitTorrent to promote Arthur Newman by releasing its first seven minutes for free. Seven minutes of a movie may not be very much—basically an extended trailer. But Cinedigm is hoping that you’ll be so enamored of Colin Firth’s bumbling eccentricities and Emily Blunt’s sullen expressions that you’ll buy a movie ticket to see the film in theaters.

“It’s a promotional play on one of the biggest platforms,” Jill Calcaterra, the chief marketing officer at Cinedigm, wrote to Bloomberg Businessweek in an e-mail. “We are simply taking the way [BitTorrent] has been used in the past and turning it on its head.” In that sense, Cinedigm’s marketing move is a turning point for the industry—not unlike going into business with the guy who stole all your lunch money in middle school.

Ever since BitTorrent was launched in 2001 by a computer programmer named Bram Cohen, it has had a contentious relationship with old media. Unlike digital piracy’s forefathers such as Napster and Limewire, BitTorrent has never been declared illegal. It doesn’t connect people to their desired download, it just helps them figure out where to find it. It offers a lot of legal content, too—more than two million files, in fact. But a 2011 study by piracy monitoring company Envisional found that 64 percent of BitTorrent’s traffic—which accounts for about 11 percent of all Internet traffic—came from people downloading non-pornographic copyrighted material. According to the website TorrentFreak, over 200,000 people in the U.S. have reportedly been sued for copyright infringement in recent years, usually for having downloaded things using the BitTorrent protocol. (That number is a couple of years old; the current total is likely much higher.) In 2010, Voltage Pictures filed a lawsuit against what would ultimately grow to more than 24,500 people for illegally downloading The Hurt Locker on BitTorrent.

The service, while a movie producer’s worst nightmare, is also a marketing dream: in terms of demographics, nearly half of BitTorrent users are over age 18 but under 35; 64 percent are male. What’s more, studies have shown that people who pirate movies and music online also buy more movies and music than the average person does. A 2012 American Assembly study puts the increased purchases at around 30 percent, which more or less fits with BitTorrent’s self-assessment; the company claims its users buy a third more albums and DVDs than most people. (Makes sense, right? If you’re downloading a pirated copy of Paul Blart: Mall Cop, you probably watch a lot of movies—sometimes even in theaters).

Cinedigm isn’t the first to try to harness the power of BitTorrent as a vast marketing vehicle. Last year, when Counting Crows was promoting a new album, the band released bonus songs, liner notes, and other material on BitTorrent to promote its tour. “Counting Crows were able to upgrade their entire European tour to stadium level because they could prove they had the audience through their BitTorrent campaign,” says Matt Mason, vice president of marketing at BitTorrent. Similarly, musicians are increasingly warming up to the idea of streaming their albums for free on iTunes (AAPL) and Spotify. Film studios are following suit with Netflix (NFLX), Amazon (AMZN), and BitTorrent. Sure, Cinedigm is giving you only seven minutes of Colin Firth, but that’s more or less the equivalent of a record company agreeing to release one album track for free.

For BitTorrent, the partnership with Cinedigm is a step toward legitimacy, part of an image overhaul to have people view it as an actual technology company, based in San Francisco, with over 100 real employee—and not, as Mason puts it, “this amorphous thing that only exists online.”

“It’s funny,” Mason says. “The first time I met [Erik Klinker] the CEO of BitTorrent, I said: ‘Wait you have a CEO? I thought you were a software protocol, not a company.”