I think the offer of buying series 1 programmes is aimed at members who joined after series 1. I joined right at the beginning, and I just checked. I can now watch all the wonderful old stuff again on line.
Mind you, I very, very stongly recommend that you buy the dvds when they come out, even if you have watched the programmes on line. It's easier on the eye to watch the programmes on a large tv screen.
Lorchen