alt Hacker NewsThere are more great improvisers, in other traditions, e.g. Sietze de Vries (1), who's Dutch and improvises mainly in Northern German Baroque style (the video has an improvised fugue), and Wolfgang Seiben (2), who's German and improvises more in late Romantic/early 20th century style.
However, these improvisations differ quite a bit from theatrical improvisations. All are virtuoso, but the classical traditions emphasizes structural elements, such as a uniting theme, counter-point, and development, whereas movie accompaniment is more fragmented, and builds on common musical experience, usually popular, to evoke the right mood, and is restricted by the visuals.
Playing styles also differ quite a bit. E.g., theatre organs have all kinds of bells and whistles (literally), a complex registration system, and sometimes extra techniques such as a "second touch" which allows to play dynamic accents, which is almost impossible on church organs.