I've had some experience with xdelta patches like this, and it would never work for converting a Blu-ray rip to the sort of files you're making, not least of all being that every last bit is different between them. Even if you wanted to make sure the recipient legitimately owned the Blu-ray, whatever is being compared would have to be EXACTLY the same, meaning everyone would be forced to run the same OS as you, have the necessary hardware, and run exactly the same programs exactly the same way, and you already know how well people take instruction. It is a nice thought, but difference files like this are only really good for making small updates between two things that are ultimately similar.