What some may not recognize is that the Macy's (was Wanamaker's) organ is the largest operating pipe organ in the world. It was part of John Wanamaker's deed of gift to his childern that they had to keep it operating in order to maintain their inheritance. BTW, the Atlantic City Convention Hall organ was larger but a construction accident severed the cables to the console and they are in the process of trying to restore it.
Many famous organists including Virgil Fox have played the Wanamaker instrument. They perform noon day concerts for the public but your link about random act was one of the first that I've seen where it was used with a larger group on the sales floor.
There was an urban legend about the Wanamaker organ. Sforzando Sforzando - Wikipedia, the free encyclopedia
is the musical term for sudden loudness. This is accomplished on the organ by small, flat switches and those switches engage much of the massive organ. A blind organist inadvertently touched 3 such switches on the Wanamaker organ and her next pressure on the keyboard caused $10,000 worth of perfume on the sales floor to rattle off the counter. Needless to say, safety measures were put into place on the console to prevent an organist from doing that again.
I was fortunate to work in downtown Philadelphia for several years. I made it an effort to take my lunch hours during the Christmas season to get to Wanamakers to hear the organ. It is an experience that I'll always remember.