Looks like they were loosening up back stage before their stage performance and were probably scheduled to play on stage next. The bass player must of got called in for sound set up. You can see the bass player look as someone got his attention at the stage entrance. The rest followed shortly after that song ended.
@@dorothypartridge4209 His name is Adam Steffey, he played for the Boxcars and is a five-time Grammy award winner and has won the bluegrass mandolin player of the year from the International Bluegrass Music Association eleven times, more than any other player. Not his fault the camera man was closest to him.