Why did they win? -Choir Clip Analytics 1

This is a video of the Choir presentation that won the 2011 'How Sweet The Sound' competition. The Choir is Salvation and Deliverance Church Choir. How sweet the sound' is a Choir competition that holds annually in the U.S.A.
Hey, watch it and let me have your opinion. Why do you think they emerged winner for that year? or why do you think they shouldn't have won?