I can think of few 20th century classical performers as well-documented (or as deserving of documentation) as the mad Canadian keyboard genius, Glenn Gould. This YouTube clip from his earlier days demonstrates much of what made him fascinating to countless classical music lovers: the incessant humming punctuated by occasional bellowing, the absurd posture, the uncanny ability to stop-and-start at the drop of a hat, and (of course) the amazing technique and unexpectedly nuanced lyricism of his music:
(For a considerably less idiosyncratic experience, here is one of my most cherished recordings: Gould performing Bach’s third keyboard concerto with Vladimir Golschmann and the Columbia Symphony Orchestra — Part One, Part Two, and Part Three.)