Beautiful video. Evolution is remarkable. Like all good videos on science it makes me want to know more.
Lot of words I will not remember but what I will remember enough to google is that it is microscopic assortment and “hollowness” that selectively filters wavelengths to produce reflection that enables these beautiful “structural” rather than I guess pigment-based, blues.
Quote I found by googling, trust the source more than the quote — “Structural colors are created by the physical form, or structure, of some plants, animals, and minerals. For example, the Blue Morpho butterfly's wings have microscopic scales with tiny grooves in them; the grooves amplify blue color reflection, while canceling out every other color.” http://naturalhistory.si.edu/education/teaching-resources/featured-collections/what-makes-things-blue#:~:text=Structural%20colors%20are%20created%20by,canceling%20out%20every%20other%20color.
So in my own paraphrased and cobbled together words, structural color is different from pigment. Pigment is based primarily on the absorption of light and reflection back of some of it, while structural color is based purely on the reflection of light by microscopic structures somehow arranged to wavelengths of light.
Science is insane. Truly a remarkable world.