Apologies if this has already been posted before.
I just came across the Disney parks youtube channel. On their channel they have an episode called 'Fact or Fiction: Tunnels'. Basically the story behind the tunnels under WDW's Magic kingdom. I found it really interesting and I think it's worth a watch.
[youtube:19a2dpps]http://www.youtube.com/watch?v=1FFoLJjHICU&feature=channel_page[/youtube:19a2dpps]
A very interesting video and the rest are interesting too.
They need to make more of them though 8)
These videos are also on Virgin's on demand service, I think it's in the Travel section. They don't get updated though which is a shame, as I'd love to see more of them!