Well, when I said that it's pretty common knowledge, it's pretty common among people who actually read tech articles, and books on how stuff works. As you've seen in that thread about the functional cowl hoods, people on this board for the most part believe that it will actually vent out at speed. Simple matter of fact is cowl and windshield are high pressure zones. Area behind the cowl induction hood, is a negative pressure zone, because it sees very little air flow there. So, as the air pressure on cowl increases, air will move anywhere where pressure is less, which includes over the windshield, to the side of windshield, and right under the cowl induction hood, because that's a low pressure area as well.
Why do these people seek to open that area up, when there is nothing to be gained at all, I have no clue. They are definitely wrong thinking that it will help with cooling of the car. Some of the manufacturers who produce these hoods either follow the original formula of cowl induction systems of the old, regardless of whether the car is using a carb or not, or they just simply copy other people with out any thought to it, because who cares what the part does, as long as it looks cool and it sells, right? I've spoken to some hood manufacturers, who had produces supposedly a heat extractor hood, who could not even answer a simple question of where the vent is, and why it's placed there. To them it's just holes.