Realizations

Each year at the Academy Awards, there is an Oscar given for best musical score.  John Williams of StarWars fame usually wins for something as a point of reference.  Before movies with sound there was often a pianist or theater organist who would "play along" and supply the musical "underscore" to enhance the visual.

Before there was that in movies, there was this in the theater.  Watch it and tell me when you first realized it wasn't a movie.