While I think his claims of high delivery charges are fair, I don't think it's right to call it hidden. When pricing your book in Amazon's self publishing (I am assuming here he went through KDP), it calculates in real time the delivery charge and estimated royalty based on the price you input. There is also a blurb on the right side of the same page explaining the delivery charge, and how it applies to the 70% royalty plan (and now there is no delivery charge for 35% royalty).