In case you were wondering about the song The Roots played for Jack Black's entrance on The Tonight Show the other night, we're here to explain.  Last week, HitFix debuted this never before seen student film starring a 16-year-old Jack Black and directed by Brett Morgen, creator of HBO's new Kurt Cobain documentary "Montage of Heck." Apparently bandleader Questlove caught the tape and was a huge fan. 

Check out the full video below. His build has evolved, but it's very very much the same Jack Black we knew, way back when he was in high school.