1. Yes that was the purpose of the video which I've already said I don't agree with. You seem to be confusing that specific mantra with any interpretation that we can learn anything about nutrition from studying the diet of homo sapiens over the past millions of years (which I do advocate). Is this clear now? Because I don't think there's any way to make it more simple.
2. I agree that 'doing everything like the caveman' is stupid because they aren't sitting in front of computers, wearing contact lenses, driving cars, and doing everything that we seem to do in modern society. I'm not defending the video's point of view. Also nobody argued that supplements are 'essential to life' so I don't know where you're getting that impression. I don't even know where you get the impression that 'Paleo' people (especially the extreme ones) are all big into supplements in the first place.
However, since you (randomly) brought it up, here's an explanation: the whole point of supplements is to provide nutrients that our bodies are lacking, and this assumes that our bodies tend to operate better under certain nutritional conditions. The fact is our early human ancestors don't have GNC is exactly the point. They ate a different diet than us so they didn't need it. The idea is that the reason we need GNCs today is because our diets have drastically changed and our food sources are different. Now you don't have to agree with this, but I was hoping you would have at least knew that that is what's being argued by 'Paleo' people (the extreme kind or not).