Very good video! And while we're still searching for ways to say it precisely, I'd have to say that Yes "prolepsis is involved with numbers - and it seems to involve something "inmate" as in the example of the babies used in the video.
Before they have seen the first example of a difference in quantity, they have some kind of "etching" that tells them that difference in quantity is significant to them.
And I think that "before they have seen the first example" is where we need to focus as we try to describe a faculty of prolepsis. Not on how it gets more accurate with practice, but how and why it is there in the first place, just like pleasure and pain and the other faculties are also there at birth. Focusing on adults forming conceptions of oxes after seeing more and more of them is not the place to look.
I think this video illustrates the best way forward is to look again at babies, just like with pleasure and pain, at a time period when Nature is fully in control and there is no possiblity of corruption through mistaken opinion.