The fantastic acapella group, Pentatonix, sing Little Drummer Boy.
There are no instruments; all the sounds you hear are made with their voices only.
Click the Link.
Two of Chris Gerritz's old PHI KAPPA PSI fraternity
brothers do many of the videos for the Pentatonix. Jimmy Bates and Reilly Zamber formed a company they call Fifgen Films. Jimmy Bates (Fif is his nick name because he is the fifth Jimmy in his family according to Chris) wanted to make movies, but is meeting with a great deal of success working with Pentatonix, collaborating on YouTube videos. They get paid for views and ad clicks. Their video have had millions of clicks.
The following video was done in a dorm room on a $120 budget. The guys from the group went to second hand shops in Corvalis to buy their costumes. This video has had over 110,000,000 views.