Yeah that part has nothing to do with me and I guess an option to not download DX would probably prevent that but really I assume if you choose yes it probably just checks the latest version against what you have. If it needs to download something it does if not it just finishes At least that is how running the DX installer from MS works, if you have the newest version it just tells you so and it doesn't install anything. I imagine most of the users just let it run.