Banksy 1, Oliver Stone 0

One is a major heavyweight portrait of a serving leader, by a world-famous Hollywood director, the other a micro-budgeted niche riff on a man who never shows his face. But while the first – Oliver Stone's study of South American leaders, Hugo Chávez in particular – South of the Border, failed to whip up much interest in the countries in which it was shot, Banksy documentary Exit Through the Gift Shop emerged as the top-grossing limited-release documentary in the US so far this year, Variety reports. The most glaring difference between the two looks to be marketing spend. Stone went on a whirlwind tour of Latin America to promote South of the Border, yet in the 12 days following release it grossed only $18,601 (£12,547) on 20 screens in Chávez's Venezula, according to Global Rentrak. Free screenings in rural areas did, however, attract crowds: some 1,300 people are said to have sat in front of mobile screens in the towns of Vargas and Guárico. The low turnout is said to be in part down to Chávez not having officially rallied people to go and see it. Last year, Michael Jackson film This Is It became the country's highest grossing documentary, earning $2.1m. Exit Through the Gift Shop, meanwhile, has earned $2.4m in the States. Yet the men who promoted it went for a purposefully muted campaign, eschewing big-spend ads and posters for the power of punter-generated viral buzz. A wave of Twitter, Facebook and Foursquare activity was monitored and responded to by the PR company. "If the film was sold out at 7pm in a market, then we'd tweet, '7pm is sold out – 10pm is available'," says Marc Schiller, CEO of boutique media agency Electric Artists. John Sloss represented the film at Sundance, were it became an unexpected hit, and decided to release it himself through his Producers Distribution Alliance label. "We know for a fact that the people who were coming opening weekend are not regular moviegoers," he says. "They don't read the newspapers or traditional movie advertising – we were connecting with them online, from within their community."