LA Reid: 'Rejecting GaGa Was My Biggest Mistake'
The X Factor USA judge opens up about how he passed on pop megastar...
Britters surprised the music exec backstage at the show's stop in Kansas - leaving him stunned.
As Britney and her fiance Jason Trawick finish singing, he says: "You're the sweetest in the world, oh my god, thank-you."
Mario Lopez and Khloe Kardashian are reportedly being lined-up as presenters for the show.