(VIDEO ONLY) With only five members, the a capella group Pentatonix is one of the most popular musical acts of this Christmas season.
Their 'Mary, Did You Know?â? music video is set in a candlelit cave, where, just with their voices, the group members belt out this tribute to Mary. It currently has over 14 million views on YouTube.
Pentatonix formed in 2011, when they competed and became the victors of the TV show The Sing-Off before rising to global fame.