"Johann Sebastian Bach: Fantasia G-moll" was Czech animator Jan Svankmajer's second work in a career of many animated movies he would go on to make. Unlike his first, "The Last Trick" of 1964, it shows a bit more of the filmmaker's style in what it presents, hinting more strongly at what he would produce in later years. As other reviewers have stated, it is not nearly as complex nor as weird and surrealistic as those later movies, and thus not a good place for those interested in his output to begin, but as an early effort it shows how he can evoke a certain atmosphere out of putting appropriate sound to the proper image, which was undoubtedly the film's main goal.
The first minutes of the nine-minute film are entirely live-action, as a man enters a cathedral, climbs the stairs to the pipe organ, and after stuffing a whole apple (albeit a small one) in his mouth for no reason, he begins to play the Bach title piece. The rest of the work is a series of simple animations of cracks in stone walls growing and shrinking, doors opening by themselves, iron bars on windows, and other mechanical devices. Although basic compared to what he would later produce, the music fitting well with the dark images (the film is rendered in B&W) is enough to make it work and creates a fine music video. I would not consider it a masterpiece as have other reviewers, but it works on its own level and shows what Svankmajer would later go on to create.