Would anyone dare summarise it?

Morality is a sense, similar to taste or vision. If I eat a food, I can react by going 'yummy' or 'blech'. If I observe an action, I can react by going 'good' or 'evil'.

Just like your other senses, it's not 100% reliable. Kids eventually learn that while candy is 'yummy', eating nothing but candy is 'blech' - your first-order sensory data is being corrected by a higher-order understanding (whether this be "eating candy is nutritionally bad" or "I get a stomach ache on days I just eat candy").

The above paragraph ties in with the idea of "The lens that sees its flaws". We can't build a model of "right and wrong" from scratch any more than we could build a sense of yumminess from scratch; you have to work with the actual sensory input you have. To return to the food analogy, a diet consisting of ostensibly ideal food, but which lacks 'yumminess', will fail because almost no one can actually keep to it. Equally, our morality has to be based in our actual gut reaction of 'goodness' - you can't just define a mathematical model and expect people to follow it.

Finally, and most important to the idea of "CEV", is the idea that, just as science leads us to a greater understanding of nutrition and what actually works for us, we can also work towards a scientific understanding of morality. As an example, while 'revenge' is a very emotionally-satisfying tactic, it's not always an effective tactic; just like candy, it's something that needs to be understood and used in moderation.

Part of growing up as a kid is learning to eat right. Part of growing up as a society is learning to moralize correctly :)