Brenton Langbein’s late exchange of bows

About to receive the downbeat of the opening to a concerto, Mr Langbein suddenly discovers that something is wrong with his bow. He swaps his bow with that of the leader (Sam Bor??), who does the same thing to his colleague, who does likewise to another and the bow passes conspicuously overhead across the stage from player to player. Meanwhile, the conductor, unaware, has started the piece and the rest of the orchestra plays the first bars of the concerto.