Director Erik Anjou and Frank London first began collaborating after they had been introduced by filmmaker Pearl Gluck. Frank was writing the musical score for Erik’s “A Cantor’s Tale,” the beloved documentary about Cantor Jack Mendelson. It seemed natural for Erik to start attending more and more Klezmatics shows. He was stunned by the depth and beauty of the band’s music, and the musicians’ ineffable resilience and courage. “Why isn’t anyone making a movie about these guys?” he asked.