Even Britney Spears, who's performed in front of millions, still gets stage fright.

In the new documentary that aired last night, I Am The Femme Fatale, which chronicled the pop princess' return to the stage after a year, Britney admitted, "I haven't been out [on stage] for a year... I have jitterbugs," before her surprise Las Vegas performance last week.

The cameras also caught the sexy singer shooting her new music vid, Til The World Ends, of which she said, "It was a little much. It was grimy and sweaty and it felt like there was poop everywhere... but it was just sweat."

Britney, who famously suffered a breakdown in 2007, seems to have gotten her life back on track with a routine that includes sons Sean Preston and Jayden James.

"I have two children, so I usually get them up in the morning, and I'm usually at the gym, and I help cook dinner sometimes ... a lot of the stuff that I do I do early in the morning when my boys are at school," she said.

Britney's about to embark on new tour, which Enrique Iglesias just recently pulled out of. Rumor has it he'll be replaced with Nicki Minaj, which would make it the hottest. tour. ever!

As for her new album -- click below to see what she said was her favorite track!