Is Downwash a Myth in Lift Theory?

[Wing 11]

Doug Mclean talk about common lift misconceptions.I agree with most of what he said but he claims that downward air flow "downwash" do not exist because integral is zero.

I don't agree with this statement,leave mathematics and see what happening in real world.
Downwash evidence:


What do you think about that and which lift theory do you support?

 

[A.T.]

but he claims

How about a timestamp given it's a long lecture?

 

[Wing 11]

How about a timestamp given it's a long lecture?

41:00 - 47:00 min

 

[A.T.]

but he claims that downward air flow "downwash" do not exist

He doesn't say that. He just says that the downward momentum doesn't accumulate in the atmosphere as a whole. The increased reaction from the ground cancels it.