This laudatory but not quite fawning 93-minute documentary takes a greatest-hits approach to the life and song of the now 88-year-old agit-folk musician. And surely Pete Seeger has earned the right to talking-head testimonials from Bob Dylan, Joan Baez, Bruce Springsteen, and company. Shallow, very officially sanctioned, and overly compressed, The Power of Song plays like a PBS infomercial for the inevitable DVD box set, which will surely include even more archival footage. Director Jim Brown is perhaps too determined to prove the obvious: that Seeger has lived a long, full, admirable life. (Even today, he loves chopping wood, as did his dark historical double, Ronald Reagan.) Bonnie Raitt aptly calls him “a bridge” between prewar folk and its equally political, boomer-era revival. An end-credit antiwar song (“Bring ‘Em Home”), performed with Billy Bragg and Ani DiFranco, extends that bridge to Iraq. Yet today the fan base for Seeger, himself a WWII vet, is mainly the AARP demo. My favorite moment in this blandly affectionate tribute comes when an excited grandmother rushes up to Seeger in Washington Square Park like a tween spotting Justin Timberlake. They may be old now, but the music still carries the passion of youth.