Entertainment mogul and the man responsible for discovering pop icon Justin Bieber, Scott "Scooter" Braun, threw a lavish 30th birthday bash on Saturday night at the Music Box Theatre in Hollywood. Considered by some to be one of the most powerful men in entertainment under the age of 30, the birthday boy rang in his 30s with a star-studded, over-the-top soiree complete with surprise performances by some of the biggest names in the music industry. And ET has the exclusive performance footage!The night started off with an exclusive dinner, where Scooter was roasted by close friends and family in which best friend and business partner Usher Raymond served as Master of Ceremonies. After the dinner, the night quickly turned into a bustling party. Guests in attendance included Justin Bieber, Kim Kadashian, Mary J. Blige, Adam Levine, Paris Hilton, Nicky Hilton, David Katzenberg, Jaden Smith, Wilmer Valderrama and Rita Wilson.At about midnight, Scooter, suited up in silver, turned the spotlight on Usher, who promptly got onstage to perform some of his biggest hits. Within minutes, pop phenomenon Justin Bieber joined in on the fun and crooned his hits "Baby" and "Never Say Never" with buddy Jaden Smith to the star-studded room. Bieber then gave his birthday present to Scooter — a surprise performance by MC Hammer! The hip hop legend performed new songs and old faves including "Too Legit To Quit" for the excited audience. The party kept going with additional impromptu performances by Asher Roth and "The Voice" hottie Adam Levine, who sang Maroon 5 hit "This Love."Continue reading...