, the actor. >> reporter: not only is there an animated version from jack black and jason seigle -- ♪ll ferrell and john c. riley. >> are you is new butler? >> it's been a long time. >> reporter: a short by short recreation of the original, right down to bing's baby blue cardigan. ♪ >> reporter: we tracked down the composures from the 1977 crosby special and reunited them at the hollywood musician's institute. they told us the original duet almost didn't happen. >> david walked in, said, god, i hate that song. >> can we do something else? >> reporter: so, what did you do? >> we came up strong. >> reporter: knowing it was too late to do a different song, the composures decided to improve the original. >> we decided the best way to do it was to write a counter melody, leave "the little drummer boy" alone. don't touch that. and we would write a counter melody. and we decided to call it "peace on earth," which is "greensleeves." ♪ >> harmonically -- it's a melody that rides over the -- ♪ >> reporter: how long did that take to bang out? >> about 20 minutes. it was beat the clock. >> took i