No electronics, she just stood still and the patterns were projected on to it - notice how with the very slight movement of the fabric the folds move, but the projected display doesn't.
I didnt see any links to the footage, but Carrie Underwood did in fact wear an LED dress at one point, whether it's the same as the one you guys are talking about or not i dont know.
But this isnt really too new, as Raven Symone wore an LED dress (i think she designed it herself) on one of the episodes of "That's So Raven" where she was trying to impress a sponsor for marketing the dress but the dress shorted out and kept giving her very uncomfortable shocks It was funny. That was some 6 or more years ago.
I didnt see any links to the footage, but Carrie Underwood did in fact wear an LED dress at one point, whether it's the same as the one you guys are talking about or not i dont know.
It clearly explains about the dress, which was simple material that had the effects projected on to it - no LED's, no electronics or anything clever at all