>> two hour celebration show cased chart topping acts. sharing the stage with the top 12 finalists including fall out boy, steven tyler, pit bull and ricky martin. and the judges got in on the action with keith urban rocking a solo turn before reuniting with jennifer lopez and harry conic, jr. for a medley. >> when i was showing them quips from year, i leaned over and said when this happens this time next year i'll probably be balling my eyes out. >> it was nick's night and advice for his post idol career came pouring in. >> it's about the songs. he's got a great song with that song he just sang. if he has an album of socngs lie that he'll be fine. if you want to have a long career, write songs every day.