Wild salmon have their characteristic color because they are eating organisms that contain the naturally occurring Astaxanthin. Farmed salmon subsist on grains, fish oils, etc and come out looking grey unless pigments are added to their feed.
interesting, the Salmon I have caught has not been as colorful- I mostly fish in the rivers though
edit: it looks like that vid had some steelhead (trout) mixed in? This is more like what I have seen, but the color is even more "dulled" in person https://www.youtube.com/watch?v=e09UmeqAd4g
https://en.wikipedia.org/wiki/Astaxanthin