The suspect, who was scheduled to perform at the show, was feuding with rapper Maino, who is based in Bedford-Stuyvesant. Maino had just left the stage when his rival fired at least five shots from a 9-mm. handgun in a green room above the stage, sources said. Video shows the 33-year-old gunman barging into the backstage area just after 10 p.m. sporting a gold chain and opening fire as people scurried for cover.