VIDEO: 'Sing' Movie Cast & Jimmy Fallon Sing 'Wonderful Christmastime' A Cappella with Paul McCartney!

The cast of the movie Sing – Reese Witherspoon, Matthew McConaughey, Scarlett Johansson, Tori Kelly, and Seth MacFarlane – are the latest stars to get into the a cappella booth with Jimmy Fallon for a fun video on The Tonight Show! The stars sang a cover of the classic song “Wonderful Christmastime” alongside The Roots