Madonna screens new documentary

When Madonna's new documentary, I'm Going to Tell You A Secret, premiered in New York, she was nervous the audience wouldn't like it.

"It was like, 'Oh my God, oh my God, I hope I did the right thing. Just worrying the whole way, biting my fingernails off," the singer said.

The documentary is a behind-the-scenes look at Madonna's Re-Invention Tour. "When I got to the end of it [the screening] ... I could feel that people enjoyed it," she said. "That was a huge relief for me."