I like the animations but, and I might be wrong, the descriptions and animations seem to refer to Absolute Colorimetric and Relative Colorimetric rather than Relative Colorimetric and Perceptual
My understanding of Perceptual would be that you imagine a larger circle enclosing the out of gamut colours then shrink the whole circle and contents to the smaller size, so in effect every
colour is shifted.
Also the article dismisses Absolute Colorimetric as something used only by medics
when its commonly used by PrePress to convert cmyk to a larger multi-ink space on an ink jet proofer.