Pentatonix's Christmas spirit cannot be contained. The a cappella group has released a flurry of spirited videos this month, including a "Winter Wonderland"/"Don't Worry, Be Happy" holiday mash-up with MTV Artist To Watch Tori Kelly and an original single, "That's Christmas To Me".

On the eve of Thanksgiving -- a.k.a. the official kickoff to the winter holiday season -- the YouTube sensations have dropped a hauntingly beautiful cover of the classic Christmas carol, "Silent Night."

The Austrian hymn is nearly two centuries old, and it's been covered by everyone from Mariah Carey to Sinéad O'Connor -- and even Justin Bieber.

"Silent Night" can be found on PTX's recently released holiday album, That's Christmas To Me.