Avi Kaplan sings two tones at once AND Kevin Olusola's amazing live cello beatbox

For this concert, 11/14/12 at Lincoln Hall in Chicago, Mitch Grassi (high tenor) was sick. Instead of performing the songs that feature Mitch as a soloist, Pentatonix instead decided to showcase its non-acappella talents :D Skip to 2:40 for the cello beatbox.