It's been 40 years since a half-million young people turned up at a muddy farm in New York State for an event that's still celebrated as a major cultural moment. The concert, lost money, but a year later, a documentary film more than recouped the promoters' losses. "Sex, drugs and rock 'n roll" didn't begin at Woodstock, but the film brought the counter-culture into America's mainstream. It was “3 days of peace and music” that dramatized opposition to the Vietnam War and raised questions about politics and commercial values. At the same time, it popularized illegal drugs, helped create a conservative backlash and showed promoters new ways to make piles of money. We look at the Woodstock paradox 40 years later.