Only the grid is colorful, the rest of the video is in grayscale, but the lower resolution of our color perception makes the color assimilate/blend into the grayscale cells within the human visual system.
For the original 7min44s short film full video: https://www.youtube.com/watch?v=WhWc3b3KhnY
More information and still images with the same color assimilation grid illusion: https://www.patreon.com/posts/color-grid-28734535
