The purpose is to defuse the light, but the amount or the effectiveness , that is highly subjective. Hence the comment on the video.
I don't think comparing something with your eye and claiming because the material is any different or the classification is any different, that it won't "defuse light". A piece of paper over a light source will defuse light. Generally anything white or opaque will do the trick. I think what you mean is effect of the corals is different.
Granted the material might increase or decrease the amount of light passing through the object. I've personally seen the Kessil diffusers and I wasn't impressed by them. My knee jerk reaction is "shoot I can make that"
There are more advance diffusers out there that use refractions and multiple discs. I would be interested in seeing the cross section of one that you find more advanced
@dantimdad .
As to the Pringles lid, I have a light meter and a Prime, I'd happily test the idea for you.
If you notice the bottom of the Prime Diffuser's pictures you can see that they have used a Grid to reduce the light spread and focus it more as a beam. I'm sure I could employ that to this as well. The only caution that I would take is that the light might generate enough heat to melt it or warp it - 2 cents