Victor Borge (1909-2000) was a famous Danish comedian, conductor, and pianist. He was well known in Denmark before World War II but had to move because of the Nazis. Victor moved to the United States and became monstrously popular on the radio and television in the United States and Europe. in 1953, Borge started a one man show at the John Golden Theatre called Comedy In Music which became the longest running one man show in history with 849 performances.
In this video (made in 1937), Victor Borge is playing the part of a piano tuner. He starts by testing the pianos. He then does something amazing which has to be seen to be believed. Enjoy.