I still don't understand what exactly you're talking about. Are you talking about sand used for concrete or sand in general (e.g. - for subgrade soils).
Sand used in concrete needs to meet a gradation requirement. The gradation requirement uses all sizes of sand as aggregate.
And if we are comparing credentials (which I assume is what your building construction story and youtube link is for?), then I've done nothing but put holes in the ground and fill them up with concrete for almost a decade. Here's what I was doing in 2014: https://www.youtube.com/watch?v=E4Ixw69woSA
I did the construction globally, from USA to UK to Saudi Arabia.
I'm talking about both sand in construction and in general (like for glassblowing, etc.) Portland cement uses the finest sands possible for holding concrete aggregate, which you only really tend to find in desert areas (if you're lucky enough to find a spot that hasn't been above water for more than a million years, that's one reason construction-grade stuff is so hard to find.)
Now days, I do very similar to your link, except it's through mountains, and terminates inside the mountain. Minerals extraction is fun!
Sand used in concrete needs to meet a gradation requirement. The gradation requirement uses all sizes of sand as aggregate.
And if we are comparing credentials (which I assume is what your building construction story and youtube link is for?), then I've done nothing but put holes in the ground and fill them up with concrete for almost a decade. Here's what I was doing in 2014: https://www.youtube.com/watch?v=E4Ixw69woSA