I think that's probably part of the point. If he revealed that it's just (up to) 2 hours of him going 'let me out! let me out! let me out! let me out!' nobody

I think that's probably part of the point. If he revealed that it's just (up to) 2 hours of him going 'let me out! let me out! let me out! let me out!' nobody would take him up on the challenge.