If you try to play a media file that your Ubuntu system doesn't have
the right player and/or codec for the file, does Ubuntu ask if you want to
install the right stuff to play it? Or, do you just have to know that you're
supposed to install the "restricted extras" packages?

When I set up my first Ubuntu box, I didn't install the restricted extras. Why
would an average user need or want to install something that's "restricted"?