Pentatonix Save the World mashup

MAKING MUSIC WITH THEIR MOUTHS: As you've probably heard--especially if you're trying to book a vacay in Mexico--today's the last day before the Mayan apocalypse. But what will that apocalypse be like? Rivers of blood, winged skulls and eternal darkness? Or will it be like TV's Revolution, where the power goes out and our networked civilization falls apart? If it's the latter, you'd better learn to sing a cappella. Fortunately, this video contains a master class from wholesome harmonizers Pentatonix, who offer "Save the World/Don't You Worry Child," a Swedish House Mafia cover mash-up tailor-made for an end-of-the-world party. You can catch the band on tour in 2013--if there is a 2013. (12/20p)