With innovative collaborations including the one famously done with Rihanna and Kanye West on "FourFiveSeconds," there's been some debate about what Paul McCartney means to rap's future. However, there is no debate what the legendary singer does for a music festival including this past weekend when Paul headed to the woodlands of Dover, Delaware for the fourth annual Firefly Festival

On Friday, the famous Beatle rolled up and greeted the camera man in song before being serenaded and presented with a cake by the crew backstage to celebrate his 73rd birthday that was the day before. Nothing may be as special as the clip of Paul singing "Let It Be" backstage. But there is also the gratifying wave of electricity that takes over when he hits the stage or the victorious fist slow-motion pumps in the air that are giving me chills still days after the event. Watch the video above and catch Paul McCartney live at one of his Out There tour dates including a show at Lollapalooza later this summer (dates here).