The discount system does indeed work, and I was able to go back and retrieve the discount coupon for the new Print tutorial. However, I only worked out what to do by searching through this thread. Should there not be a button on the store page for the tutorial that gives the step-by-step, i.e. log in to your account, locate your original receipt for the first Print tutorial, download the extras, copy the discount coupon number, etc.?
In any case, thanks to all for all the hard work; I'm looking forward to these new tutorials immensely.