Insulation is an area with a lot of snake oil solutions and a lot of just general ignnorance/naivety (the popularity of reflectix in van builds being an example of this), and a lot of products that might work well in some certain context but not as a general insulator.
With that in mind, any insulator that doesn't provide technical details, or that sounds too good to be true, I generally assume
is too good to be true, regardless of youtube/customer reviews, and that sort of thing. Placebo is real, and there are many people that rave about reflectix insulation in their van or skoolie, and many people on youtube/instragram/etc professing the miracles of nearly any product under the sun.
I'm not saying the couple in the video is wrong or that the product is not legit (it might be) but I think skepticism is a reasonable baseline assumption for a
technical product without easily accessible technical details (most importantly R-Value), that is claimed to far exceed other more reputable products on the market. In some cases its true, in most cases its not.
However, it is possible that for the limited application of between the metal ribs and furring strips it might have some value, I don't know.
This is the website for anyone interested (looks like it was last updated in the late 90's)