You Tubers receive copies of game books all the time. Most will show a lot of the book in their reviews. Companies never complain, in fact, they love the potential new sales reviews bring. You Tubers did the same with the PHB and WotC reacted poorly. Naturally, there was panic and dismay on the You Tubers side when one of them got a strike notice and others were given instructions after their videos were released. It was a case of WotC not getting their ducks in a row, and it caused unnecessary stress.
WotC needs to quit freaking out over piracy. Yes, it's wrong, but it will not hurt them if reviewers show pages of their books. In fact, if WotC released pdfs, there might be a reduction in unauthorized copies. I doubt that blurry stitched together copy dented WotC sales in the slightest.