Their song “If You Want to Be a Bird” was on the Easy Rider soundtrack, but that’s as mainstream as NYC’s Holy Modal Rounders ever got, unless you count the time they were on Laugh-In. This slapdash doc explains why the pre-Dylan psychedelic folk duo of Peter Stampfel and Steve Weber was destined for obscurity. (In short: drugs.) Weber’s acid-driven eccentricities are the star of the film, until he withdraws permanently in 2002, just before the band’s 40th-anniversary reunion, perpetuating a historic habit of sabotaging the group’s success at crucial times. Much like the Rounders’ career, the film is a disorganized effort dotted with moments of brilliance.