Squeal!! One Direction performed on 'X Factor' for the second time this season, bringing their brand new single 'Kiss You' to the season finale (Dec 20). The group is the biggest act in the history of the show, even though they didn't win when they appeared on the British edition. Look at 'em now! We still shake our heads in disbelief, so much so that we get a headache, over the fact that they didn't win in 2010! WTF, U.K. viewers?