I do not believe the time was that dimension inside the balloon analogy - it was a fourth spatial dimension. I just listened to the followup Q & A show and that reinforces this view.

The current thinking is there is probably 11 or more dimensions to the universe(s). But for the discussion on the shape and size of this universe, I think we can stick with three we experience, at least extra spatial dimension for the curvature of space in a way we cannot perceive and then one for time.

And, yes, this trilogy on the shape, size, and center of the universe is one of my favorites. I am almost done with the current Astronomy Cast! It is sooooo kwel - one of the best finds on the Net that I have heard in years!

I promise to donate right after I recover from the bill I have to pay to the warlords on April 15th.