Britney Spears’ Dingy Dressing Room, a New Bieber Song, and More Candid Celebrity Clips!

Stars who are savvy with social media have been sharing more and more behind-the-scenes videos with their fans. This week, Britney Spears showed off the dingy locker room she had to get glam in, while Justin Bieber and Jimmy Fallon turned the camera on themselves to share the start of a new funny duet. Check out those clips and even more fun footage in today’s PopSugar Rush.