Uh, it doesn't quite work like that. You don't think the suggested retail price of every DVD reflects its production cost do you? There is sort of a standard price out there for DVDs that has nothing to do with production expenses. Of course the Yoda scene does not make the price of the DVD go up, but it could be time and resources spent on other things. And it does cost a lot more than a buck to make. That video is a lot of work behind a computer, and the employees have to be paid for it.
Why does this bother you so much? Several people think it is stupid and for some reason you can't seem to live with that. It is okay if it gives you kicks. I am sure a lot of people enjoy watching rap videos staring little green men.