The audience member is correct. Myopia is caused by light entering the eye being focused in front of the retina by our natural lens and cornea, this is usually as the result of increased axial length i.e. elongation of the eye.

The dangerous thing about this talk is that the first 2/3rds are true. Reading, looking at screens and working up close as a child and young adult do cause progressively worse myopia by way of progressive elongation. This isn't controversial at all. There's no evidence that spectacle use influences progression.

The latter 3rd is all bullshit. While our eyes continue to grow and elongate until around our mid 20's, there's no mechanism I'm aware of that can shorten the eye which is what you would have to do to "reverse" myopia. This is more or less common sense.

There are studies that show that low doses of atropine given to children who are myopic with reduce the progression, but not reverse pathological myopia. At this point we're just waiting on FDA approval of a low-concentration atropine drop. I suspect that in the near future the prevalence of high and pathological myopia is going to decrease dramatically.