Hey, ASPers, I really like your idea and good job on getting it developed so well! I think to really nail you you have to become more specific on the influence people's activity has on the show. So what type of show is it, is some mystery getting solved - people usually relate to that well? Or the fate of some character (lives or dies) depends on the effort put in by the public? I think you need to raise the stakes for the people in front of the TV - think about what would make you send a paid message to a tv show? Now, you have to motivate even beyond that since you are expecting a physical activity as a behavior.
Just as a flash idea - there was this interactive theater play which was a murder mystery where the voting of the audience decided who the murder was and how the actors need to end the last 20 minutes of the play. I went to that play many times just to see the effect of the different endings. Maybe it could give you some idea for the nature of the show you are looking at. If you manage to get the motivation really specific and convincing, I think you have a winner :)
And another thing I thought about is also thinking on how you can get people to get together and exercise together in synchrony (or something like flashmob) and the more you manage to get the more effect you have on the show...something along those lines. Because watching TV is a bit of a non-social experience in itself. Could you use your idea to turn around the stereotype of what watching TV could become?
And last - I know you are counting on a lot of using technology people are already used to - but I think it might also be useful for your team to consider implementing new technologies like Kinect, Oculus Rift and the like? It would add an additional challenge but it would catch the hype that those gadgets are going to become as soon as they enter in the mainstream. And it would add strength to the buzz around the show. For example the best team effort gets Oculus Rifts and moves the characters during next-weeks show... (I don't know if the show could be animation for example...?) This way you can get the producing companies to sponsor the idea because they get visibility to their products.
Anyway, great work and I am really crossing my fingers for your idea! Cheers :)