Host Nick Lachey talks about this season's dynamics, the challenges of singing a cappella and why he loves the holiday season. The Sing-Off airs December 17 at 9/8c.» Subscribe to NBC: http://full.sc/y8sIqDGet more NBC:Full Episodes: http://NBC.com/video/library/full-episodes/NBC YouTube: http://www.youtube.com/nbcFollow NBC: http://Twitter.com/NBCLike NBC: http://Facebook.com/NBCNBC Tumblr: http://NBCtv.tumblr.com/NBC Pinterest: http://Pinterest.com/NBCtv/NBC Google+: https://plus.google.com/+NBCYouTube: http://www.youtube.com/nbcNBC Instagram: http://instagram.com/nbctvThe Sing-Off - Nick Lachey (Interview)http://www.youtube.com/user/NBC

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