This is Pentatonix, a five person a cappella group who post videos of their covers onto YouTube periodically, tour around the world, and have put out two albums that you can find on iTunes.
They cover a lot of chart topping hits and tend to stay fairly current with their music. I was introduced to them a little over a year ago by my lovely roommate and given the opportunity to see them in concert in Ithaca. It was the best concert I have ever been to. They are young and charming and personable. They are also wildly talented. I encourage everyone to check them out, as they are a really great group to get to know if you are a fan of genuinely talented singing. In a world of auto tuning, they are talented people who sound just as good on the stage in front of you as they do singing out from your headphones. The video above is one of my favorite of their covers and the one below is their most recent, and my new favorite. Check them out on Twitter, Instagram, Facebook, YouTube and probably more besides.