'Little Drummer Boy', the latest viral video by Pentatonix brings in the Christmas season

Pentatonix is an a cappella group of five vocalists, Scott Hoying, Kirstie Maldonado, Mitch Grassi, Avi Kaplan and Kevin Olusola, originating from Arlington, Texas. The group shot to fame after winning the third season of popular reality show The Sing-Off. Since then they've established themselves as a popular group on YouTube, with a number of their videos going viral. Their recent upload, an a cappella rendition of Little Drummer Boy, a popular Christmas carol is the latest feather in their cap.