I would 100% love to see this idea take off! DVD's will not last too long as so much of the entertainment world is going digital... I think alongside the dvd's an online digital download of the Knightmare series would work and add to sales.
I am a massive knighmare fan and watched it everyday as a kid after school. Have youtubed it as much as possible to bring back the memories and often spoke of the series with my mrs and own kids!
Hope this does take off good luck.