How a Viral Video Bent Reality

“There was a large sentiment in this country that people felt they were being lied to,” Mr. Bermas said.

New technology helped, too. Unlike pre-internet conspiracy theories, which had to be passed on through books and pamphlets, “Loose Change” was available free online. Fans uploaded it to sites like Google Video, the now-defunct YouTube competitor, where it was viewed millions of times and got translated into multiple languages.

The “Loose Change” team also hit on other creative distribution strategies, selling DVDs in multi-packs, and encouraging fans to leave copies behind in laundromats, post offices, hotel lobbies and other public places where strangers might pick them up. When fans wanted to spread the film on their own, they allowed it, even if it meant uploading it to a torrent file-sharing service or passing around pirated discs.

“We didn’t care,” Mr. Bermas said. “We wanted the message to get out, period.”

“Loose Change” never made its creators rich, but the film became a cultural touchstone and attracted a number of high-profile fans. Rosie O’Donnell, then a host of “The View,” raised doubts about the official Sept. 11 narrative, and Joy Reid, now an MSNBC host, praised the film on her personal blog. (Ms. O’Donnell did not respond to a request for comment, and Ms. Reid has said that her blog was hacked.) Charlie Sheen expressed interest in narrating a version of the film, Mr. Rowe said, which would have been financed by Mark Cuban, the “Shark Tank” billionaire, although the deal never materialized. (In an email, Mr. Cuban said he thought the film was “ridiculous” and that the talks never went beyond initial discussions.)

Jonathan Kay, a Canadian journalist who wrote a book about Sept. 11 truthers, told me that the success of “Loose Change” turned conspiracy theorizing from a passive hobby into a social activity, and encouraged a new generation of conspiracists to try their hand at media-making.

“It was part of an era where anyone with a fringe theory suddenly popped their head up and said, ‘Wait a second — with a couple thousand dollars or even less, I can make my mark on the world,’” Mr. Kay said.