Before she debuted her new song before millions on “American Idol’s” season finale, Beyoncé killed in rehearsals. In this candid iPhone footage shot by Jay-Z in his wife’s dressing room, B and her band run through her performance of “1+1” as her mother Tina Knowles and nephew Julez look on. If you had any doubt about the power of her live shows, this should make you a believer.

Sometimes you need perspective. You’ve been right in front of greatness so often that you need to step back and see it again for the first time. This is the dressing room rehearsal for American Idol. NO MICROPHONE. No effects. – Andy WarHOV.