John Cage (September 5, 1912 – August 12, 1992) was an American composer, philosopher, poet, music theorist, artist, printmaker, and amateur mycologist and mushroom collector. A pioneer of aleatoric music, electronic music and non-standard use of musical instruments, Cage was one of the leading figures of the post-war avant-garde. Critics have lauded him as one of the most influential American composers of the 20th century.
from an extensive page on John Cage in Wikipedia
While it is difficult to imagine an avant garde composer as a guest on a TV game show, it seems to work quite well for John Cage. It is difficult to sum up Cage’s work and philosophy here (refer instead to the Wikipedia link above), but it is fair to say that Cage believed strongly in the practice of listening, of incorporating all sounds into our understanding of music. Even the laughter from the audience, which is not surprising considering this clip is from the year 1960 (51 years ago) when the vast majority of people watching would have never encountered anything like this.
Cage is absolutely unflappable as he goes about his business on stage, manipulating unusual objects (possibly selected in some cases for their humorous theatrical quality… good for TV) and marching back and forth across the stage.