When 13-year-old Greyson Chance posted a clip of himself performing Lady Gaga's "Paparazzi" on YouTube in April, he never dreamed that the video would become a viral sensation viewed by more than 28 million people. The clip, shot by Greyson's dad, shows the Cheyenne Middle School sixth-grader at the piano, singing his heart out at a choir event as the female-dominated audience looks on slack-jawed with amazement.