Britney Spears Has 'X Factor' Over a Barrel

The honchos at "X Factor" wanted Britney Spears so badly, they literally gave away the candy store by giving her the right to do things during production that are not "normal" ... and that includes taking breaks whenever her little heart desires.

As TMZ reported, Britney walked off the set yesterday during the first taping, leaving behind an empty judge's chair while 4 contestants did their thing.

Sources connected with the production tell us Britney was "overwhelmed" and needed to leave. People who were at the taping tell us she was upset by the audience reacting negatively to some of her comments.

Fact is ... "X Factor" wanted Britney so desperately, she was able to negotiate terms that are "unheard of" -- so say people with direct knowledge of her deal. As one source put it, "Simon is a smart and shrewd businessman who knew Britney could make his show and he was willing to give her just about anything to come on board -- and he did."

So Britney is allowed to walk off any time she wants. And that's just the beginning. Britney can do just about anything she wants ... and get $15 million in the process.