Derek Hough Sneaks Into the 'America's Got Talent' Finale, Dances with Light Balance

The America's Got Talent season 12 finale was chock full of celebrity cameos, but none were quite as unexpected as Derek Hough's surprise appearance.

On Wednesday's star-studded finals results show, each of the 10 acts that competed in Tuesday's finals took the stage yet again for an encore performance before the winner was announced -- including the wildly inventive Ukrainian dance crew, Light Balance.

Performing a shorter version of the routine that earned them the coveted Golden Buzzer from host Tyra Banks during the audition rounds at the start of this season, Light Balance pulled out all the stops to show why they are one of the most impressive LED dance groups ever.

And when the lights came up, it was revealed that they got a little help from a special guest.

Ck It Out Dance Fans @derekhough Performs With Light Balance On The #AGT Finale!! Plz Share! #RTpic.twitter.com/21pdUGjd8N

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