About the artists:

Black Violin is an American hip hop duo from Fort Lauderdale, Florida comprising two classically trained string instrumentalists, Kevin Sylvester and Wilner Baptiste, who go by the stage names Kev Marcus and Wil B. Kev Marcus plays the violin, and Wil B. plays the viola (source)

The Blind Boys of Alabama, also billed as The Five Blind Boys of Alabama and Clarence Fountain and the Blind Boys of Alabama, is an American gospel group. (source)