This a major usability mess on ImgBurn’s part IMO.
Even knowledgable users can be confused by that window (let alone average users like me). Should i choose the minimum amount of padding or the option that gives a 50/50 ratio? Does choosing a big padding cause problems with slow players? (I am still wondering about that last one).
Nero, DVDShrink and the rest don’t have such a window, they do it all automatically. ImgBurn should have an option to set this automatically too. After all, ImgBurn goes through the trouble of recommending an option sometimes, and even if all options are equally good (equally bad) it could just pick one at random, dammit.