I saw a video on TV that was supposed to be an “outtake” of that whole scene. It was not one of the regular movie cameras but an extra. this is what it was. the actors were on break and the kid started playing the banjo, one of the players of the movie picked up his guitar and that is where the whole thing started. The other actors around heard the music and came over to watch. They all thought it was so good (it was not in the script, supposedly) that they put it in the movie. Now if what you guys are saying, this whole televised outtake was a giant hoax. that is hard for me to believe as I saw the whole scene with my own eyes. Can’t remember what channel or show I saw this on though.