With regards to the first one, if you want to join the flat earth society, then you are welcome.
The second one I am sure, has never studied aerodynamics in a wind tunnel, also he isn't showing the whole picture of the way airflow goes around an airfoil section, his is missing in his ramblings the easily seen area of high pressure on the leading edge of the aerofoil. He is showing only what he wants you to see, and are in my mind, his own assumptions. Maybe he has joined the above society, and just spreading the same drivel about.
Put it this way, if you believe that stuff, then don't buy any sort of vehicle that uses a carburettor, because for you, it would never run, as it works on the same principle as an aerofoil, increased speed, producing a reduced pressure thru a venturi (a back to back aerofoil) that sucks the fuel thru the jet. Also don't ever fit a Korts nozzle, because that works on the same principle, speeding up waterflow thru a venturi, hence more thrust at the back because of increased velocity. If the above are to be believed, you would in fact stand still or even go backwards by using a Korts, by sucking water from the rear, around the outside of the nozzle and moving it forwards to the Korts intake.
There is definitely something wrong with their way of thinking, and methinks I will stick with the normal proven scientific conclusions from the last 100 years.
A standard flat bottomed aerofoil in fact doesn't need an angle of attack to produce lift, nor an increased pressure area underneath. The airflow will automatically speed up over the top surface and produce lift, not a lot, but it will make a low pressure area.
Helicopter aerofoils are usually symmetrical for most of their length, so when they are sitting on the ground and turning, they are in a state of neutral balance, only when an angle of attack is introduced do they start to produce their lift above and cushion below. The weird shapes you see on modern helicopter blades is to do with the control of air flowing from high pressure below to the low pressure above, by way of the blade tip ends, if that happens, the tips of the blades can stall, and on a fully articulated head, cause the blade to drop dramatically, to such an extent the blade can drop and hit the tail section or groundcrew at the front or side. You will also see the same sort of control on modern aircraft, with the winglets sticking up on the tips, and little air dams (fins) over the top and bottom surfaces, all designed to keep the airflow straight, to stop them meeting at the wing tips. At high angle of attacks, and usually slow speeds, you will most probably see vortex produced at the wing tip, where the high pressure from underneath is attempting to get to the low pressure above, by way of the wing tip ends, NOT over the leading edge.
Here endeth the lesson. I am sure I have forgotten a lot, but I also remembered a lot of the basics, plus a lot has happened in the design side from 20 odd years ago. But not on how they work.
John
