I like the part where they talk about the color perception space. The color perception space has itself multiple representations, according to the distance definition you are taking. The one shown in the video is the CIEXYZ (1931). Since human perception is non linear, there are other definitions which take into account those non linearities to make the space more "Hilbertian", such as CIELAB (
https://en.wikipedia.org/wiki/CIELAB_color_space), or CIELUV (1976,
https://en.wikipedia.org/wiki/CIELUV). This article sums up well the different representations :
https://math.stackexchange.com/questions/1777699/color-space...