World o' Jeff has linked to the YouTube video and has kindly given me a blog link as well. So thanks to Mr. Jeff for the kind words:
"It's a scene out of a musical- walking through Union square, and suddenly strangers begin to dance and sing- one voice at first, and soon a chorus line appears out of seemingly nowhere.
"Only it's not a movie, it's a San Francisco based performance art group calling them selves "Public Displays of Musical Affection". The Video itself is called 1...2...3:45 6/7/8. . . .Kudos to all who took part."