It has long been an argument that teenagers' desire for blue jeans and western music brought down the Iron Curtain.
The Oscar-winning director of One Flew Over the Cuckoo's Nest and Amadeus spoke to BBC News Online before the launch of a festival at the Barbican Centre in London.
The festival brings together all his Czech and American films for the first time in the UK.
It has long been an argument that teenagers' desire for blue jeans and western music brought down the Iron Curtain.
But Forman maintained it was actually the regime's criticism of the "fabulous" Beatles that punched a hole in their own credibility.
"Suddenly the ideologues are telling you this is decadent, these are four apes escaping from the jungle."
"I thought I'm not such an idiot that I love this music and suddenly these political ideologues were strangers."
Banned
Forman made his first feature Black Peter in 1963, and it was a hit at film festivals around the world.
The communist authorities allowed him free reign and Forman was prominent in the Czech New Wave - until he made The Firemen's Ball in 1968.
This film - the story of some small town firemen who organise a raffle where all the prizes are stolen - was banned for "making fun of the common man".
When Forman was subsequently invited the US to make his first Hollywood film Taking Off, he stayed.
He left behind his family and twin sons, but says he is not bitter.
"It's some kind of a self-protection but I don't think about it too much you know."
"If I went back then I wouldn't be making films at all."
Forman went on to make highly successful Hollywood movies.
His 1975 film One Flew Over the Cuckoo's Nest starring Jack Nicholson won five Oscars.
In 1984 he was allowed to return to Prague to film Amadeus, which won nine Oscars.
He also made Hair in 1979, Ragtime in 1981 and most recently A Man on the Moon.
Death camps
His films focus on outsiders, on difference, on freedom of speech and the difficulties of individual freedom.
Given his own history - his parents were killed in Nazi concentration camps and his experiences under communism - it is easy to jump to conclusions, but Forman himself is not so sure.
"People tell me that being an outsider helps, the outside eye can see things that the insider overlooks, but I'm not really aware of it."
But later he said, a touch disingenuously given his strong Czech accent and enthusiastic English: "I feel like an outsider in both now, I'm forgetting Czech and I haven't learnt English yet."
And when he explained what it was that attracts him to individual films his answer about Cuckoos' Nest was telling.
"It was that final scene because that was the dream of anybody living in communist times, to pick up something and throw it through the bars."
Forman loves to catch up ideas and throw them through bars.
His 1996 film The People Vs Larry Flynt was controversial for its portrayal of a pornographer who extracted a legal ruling from the US Supreme Court that censorship cannot be imposed on grounds of taste.
Censorship is a subject dear to Forman.
Censorship
He has in recent years campaigned against the legal ownership rules of film in the US, which he says are tantamount to censorship.
In the US the owner of the copyright, the studio, is the author of the film rather than the director or the writer.
"It's totally absurd," said Forman.
"The author of Larry Olivier's Hamlet is nether Olivier nor Shakespeare its MGM."
The irony of the fact that he left a country where they were actually censoring films to live in a country where indirect censorship is possible under law, is not lost on Forman.
"It is one of the paradoxes of my life," he said.
"In communist Czechoslovakia theoretically you were the author but if they didn't like it they changed it but in the US the studio can do whatever they like to your film."
In practice he admits: "They generally leave your film alone."
Forman's plans for the future are uncertain, though he says he is "flirting" with a couple of ideas.
A reported project to make a biopic of Spanish painter Goya with The English Patient producer Saul Zaentz was, he said, "premature".
The 69-year-old director added: "The older you get the more difficult it is to find something to get excited enough about to spend two years of your life."
He says he is optimistic about film and his own future within it.
But clearly Forman's main project at the moment is personal.
Asked what he goal he has left to achieve he said: "I would like to see my twin boys go to university."
His sons are two-and-a-half years old.