Mtnmn
If you look at the second video they talk about not deploying more then 25 degrees when engaging in combat. But it also states to use the power to run away and not turn fight. 
I didn't watch the video that far in but basically assumed that would be the case. WHY would they say that is the question though, and what makes their situation different from ours?
Obviously, the plane is designed to allow more flap usage than that, and that's because the designers found that more flap usage than that could be beneficial in certain circumstances (primarily landing, in WWII circumstances).
However, the plane won't just fall out of the sky if you use more than 25 degrees, and in WWII it was a worse idea to get slow and turn with an enemy than it is in AH.
Let's say HTC models a hammer and nail absolutely perfectly, and models a construction worker to just hold that nail at an angle determined by the user, and to swing the hammer to hit the nail. If HTC puts that into a game of sorts, could we expect real-world performance to be shown in building a structure?
No. Our worker won't get tired, his hands won't sweat (effecting his grip on the hammer), he'll never hold the nail wrong (or try to use a defective one), tire, weaken, or use poor technique with the hammer.
With our pc-interface devices and hot keys, etc, we might actually get that "old-fashioned" hammer and nail to perform closer to a real-world pneumatic tool than it would ever be possible a person with a hammer to do in RL. That's because there's nothing wrong with a hammer and nail, the weakness is with the human. If the human element is removed (by modeling or lack of in AH; by a new tool in RL) performance and apparent "skill" will be different, as will the final outcome.
Back to the flaps, turn performance isn't greatly enhanced in AH if more than 25 degrees are used. That mirrors RL, at least in theory. However, in AH we're much more free to experiment, and we've found some distinct advantages to briefly, carefully, use up to 50 degrees. IMO, that's due in great part to the ease with which we can do that, and the lack of severe penalty for mistakes. The human element has not been modeled in AH, so we don't see the human-related limits that we see in RL F4U (or any other plane) usage.