This is not the classic concert film about the music festival that started it all. But it features the same music and images, and that’s a solid foundation for a loving reminiscence of the event that defined the ‘60s generation. If you belong to that era, Barak Goodman’s film will deliver goosebumps of recognition. If you’re younger and have ever wondered why Woodstock was such a big deal, the raw stuff of the counterculture is all here: the anti-war movement, free love, nudity, drugs, communal living, abundant grooviness and, of course, epochal music. “I felt like we had gone from civilization to some place where there were no rules,” one festival attendee recalls. Sure, The New York Daily News seems to retort: “Hippies Mired in Sea of Mud.” A half-century later, as culture wars rage on, we are still waiting to see if freedom can prevail — and that’s why it was a big deal.