From the several documentaries on Gould that I've seen (some by Bruno as well), this one is the infinitely greatest. From a simple reason. As Thomas Bernahrd insinuated that Gould became the Goldberg variations, seeing this film you understand that the great extraterrestrian was an art work of his own: Glenn Gould, performed shockingly beautiful by the artist himself. And as art exists in the collective mind of its consumers, so does this film performs the Glenn Gould artwork by showing us the image in the minds of his fans (instead of by boringly retelling the mundane narrative of his life).
& the image is just amazing. Actually, I cannot describe the image in words. You'll just have to listen to the variations.