According to Dave Chappelle, it’s a universal law: all comedians want to be musicians and all musicians want to be comedians. “I’m mediocre at both,” he deadpans during Michel Gondry’s energetic concert film, Dave Chappelle’s Block Party, “and yet have managed to talk my way into a fortune.” The comedian sells himself short — he might not be a household name in Britain, but in America he’s in the Forbes Celebrity 100 list, he’s edgy enough to have retained a black home crowd (his Comedy Central programme Chappelle’s Show has had him play a blind white supremacist and enshrined the funk-friendly phrase “I’m Rick James, bitch” in US pop culture) and charming enough to enjoy mainstream appeal (“Old people love me!” he vamps on camera after wooing an elderly lady on the streets of his Ohio home town).

It’s this cultural currency that paid for the events of September 18, 2004, when the comedian colonised a sleepy Brooklyn street corner to host his own block party. This was no ordinary neighbourhood gathering, however: “socially conscious” hip-hop luminaries such as Kanye West, Jill Scott and Mos Def flocked to the intersection of Quincy and Downing to play what Chappelle calls “the concert I always wanted to see”. As if his powers of persuasion were in any doubt, he even managed to reunite the Fugees for the first time in nearly eight years, a water-into-wine miracle among the hip-hop community.

Common, the underground rapper whose Grammy-nominated 2005 album Be pitched him into the overground and who appears on several of Block Party’s key performances, explains the sense of occasion. “It was like a day of cleansing. When I saw the Fugees get on stage together — we’ve been waiting for it, needing it. And when I sang Love of My Life with Erykah (Badu, his former girlfriend), it was our first time connecting on stage since we broke up. It felt like a full-circle thing and you could see that with the Fugees too.”

The heavens might have opened during the concert but watching Block Party is a sunny experience, powered by the delirious approval of the 5,000-strong crowd, the helium-uplift of the music and, vitally, Chappelle’s solar charisma. Gondry, the director of Eternal Sunshine of the Spotless Mind and the forthcoming Science of Sleep, follows him as he hits the streets of his Ohio town, offering “golden tickets” to the “ party of the decade”. He even ropes in the marching band of Central State University, a jubilant satin-clad throng who wind up playing with Kanye West on a wonderful version of Jesus Walks. “I wanted to follow this marching band who become the spine of the film,” Gondry explains. “It didn’t cost any money, nobody thought it would have any importance, but at the end of the day that’s what makes this not just a concert movie. You feel you are going through a journey.”

Sure enough, you can almost hear the rustle of egos being put on ice as Ohio college kids breathe the same rarefied air as the Fugees. Gondry assisted the happy-go-lucky atmosphere by suggesting that the Roots act as house band for the day. “Each artist wanted to have their own line-up, and I said you would have a better sense of community if there is the same group of musicians sharing the stage, instead of spending all this time to remove equipment.”

Despite the effortless good vibes generated by Block Party, subsequent events cast the film in a different light. Shortly after the concert, Chappelle signed a contract with Comedy Central for a reputed $50 million (£27 million). Eight months later, however, he suddenly disappeared to South Africa, triggering rumours that he was overwhelmed by the pressures of fame. You could see this concert — what Common calls an attempt to be “true to who you are and to the people” — as an early warning, expressing a deep desire to “keep it real” and exchange the life of the superstar for life on the streets.

Gondry dismisses claims that Chappelle is a difficult diva. “Most comedians have this need of people’s approval and attention. Dave is not like that so I guess that makes him a real person.”

Even his “disappearance” says something about his common touch — after all, who wouldn’t freak out in the face of $50 million? Despite the shadow business and finance, however, Common still sees Chappelle — and Block Party — as being part of a bigger cause, a nobler aim.

“We all want to make a difference and leave a mark. We want to make a change and be true to our art and our selves. We all have something to say. No matter how many records we’ve sold or how big our TV show was, this was moving towards a certain cause — to encourage and inspire people to love.” And there’s nothing funny about that.

Dave Chapelle’s Block Party previews on Wednesday at the NFT, SE1 (020-7928 3232) and opens next Friday