It also utterly fails to account for the optic nerve element, or such things as why the pieces of an eye -- the retina, the orb itself, the eyelid, the muscle control, the lenses, etc -- all evolved in the same area of the body and how they work together. That is, yes, we may have a light-sensitive 'device' on our body. But how does our brain understand that such a thing exists, much less how on earth to make use of such a thing?
The complexity of eyesight is enormous, and while I understand that the forum afforded by this video doesn't allow for the detail necessary, it doesn't appear that the professor has an answer for that in any case.
Yes, the incremental steps provide advantage to the creatures involved. But how does a retina suddenly burst on the scene? A lens, for cryin' out loud?? One would expect that we'd be born with lenses on our fingernails just as often as they might appear over our newly-evolved eyeballs.
You know, looking at this video link, one would kind of get the understanding that the evolutionary development of an eye function might have been, ummm... directed toward a conclusion?
Discussing the evolution of an eye or any other complex organ is usless without first determining the origin of the cells of which it consists.