It’s been a week and a half since Britney Spears thrilled fans with a surprise Las Vegas show, and MTV was behind the scenes as she rehearsed for the big event.The network premiered "Britney Spears: I Am the Femme Fatale" on Sunday night, giving fans an intimate look into the pop star's life as she listened to her new single with Will.i.am, filmed her new music video, and prepared for her Las Vegas show.Watch to see Britney and her dancers work out the moves for her big night. (ETonline.com)