THE Brooklyn documentarians Audrey Ewell and Aaron Aites were watching live online as Occupy Wall Street started its ill-fated march over the Brooklyn Bridge. It was October 2011, and “there was this crazy drama unfolding,” Ms. Ewell said. “All of a sudden everybody is being arrested — and then the guy who was filming it said his batteries were running low, and the screen went black.”

Ms. Ewell turned on the television. “There was absolutely nothing,” she said. “No coverage of 740 people being arrested on the Brooklyn Bridge.” So she and Mr. Aites, who had made “Until the Light Takes Us,” about Norwegian death metal, took their cameras to Zuccotti Park in Lower Manhattan. “We’re not part of the movement, but we were interested, and there was this experimental aspect that appealed to us,” Ms. Ewell said. “What would happen if you took their sort of diffuse processes and turned them into a really goal-oriented project?”

The result of that experiment, “99%: The Occupy Wall Street Collaborative Film,” will have its premiere at the Sundance Film Festival next Sunday. It is one of three films at this year’s festival, along with the Arab Spring documentary “The Square“ and the Tea Party documentary “Citizen Koch,” that are racing to catch up with rapidly evolving social movements. The level of difficulty of all three films is extraordinary. At a time when digital filmmaking makes it easier to speed the news into theaters, it’s also harder to keep pace with it. Each of these films faces the challenge of describing a diverse social movement that’s still coalescing. They don’t readily present central leaders or particularly coherent messages.

“For a filmmaker it’s always a question of: What are your assets and what is the narrative approach that you want to take when you want to tell a story about something as diffuse, in a way, as a movement?” said Cara Mertes, director of the Sundance Institute Documentary Film Program, which supported all three films. “Each of these actually take different narrative strategies in order to bring you into a narrative about something that is quite disparate, quite complex.”