Are these kids serious?

New favorite button on the remote? The "Last" button. Autumn Monday nights used to be great just for the football. But now, I utilize the "last (channel)" button frequently because the Sing-off is one of my new favorite shows. I'm thankful for this show because it exhibits such incredible talent -no selling of glitz or glam- just a capella wonderfulness. I love the way they pull this off, with only voices, and the patience to put something together like this (see below) arrangement with so many sounds to coordinate... Does anyone know of a group like this around the Main Line? If so, I need to know about them!