i saw that video a few weeks ago and went to the mfgs site, tons of bad reviews on longevity of the product. People loved how they worked WHEN they worked, but i saw many reviews that said they died in a very short while
definitely do the big 3. Dont even consider not doing it. Youll not find anyone on here thats averse to the idea of the big 3 if youre running anything near 1k watts. Youll get some who will say that its not necessary, but you wont find anyone who is against the idea.
I sold a guy an A/D/S/ PS5 back in the day that he had installed by a shop (he had the shop install it because he had to have custom kicks made for the diamond audio 6.5s anyways) and they did a 4 gauge kit to a distro block so the 8 gauge run was as short as possible and they did the big 3 even on just that one amp.