It was probably a Sony Nex camera using one of the 5 inch Sony hdmi monitors. Or even a compact with hdmi output.
http://www.bhphotovideo.com/c/product/755854-REG/Sony_CLM_V55_CLM_V55_Portable_Monitor.html
As far as I know, there isn't any way to get your live view output on your iPad. If there was, I would gladly be using it myself.
The closest you can get on the iPad would be using an EyeFi card to be able to see your shots on your iPad after you shoot.
On your MacBook, you could attempt to use an external hdmi or analog capture box to preview the live view output over hdmi or composite/component. You would be able to see the feed in an editing program like Final Cut Pro 6/7. I haven't played with Final Cut X but from what I have heard, it's capabilities to capture from external devices is neutered from prior versions.
Black Magic Design makes various boxes, most of the newer ones are USB3.0, some are thunderbolt and some are just USB2.0, with varying capabilities and software compatibility depending on how much you spend.
http://www.blackmagic-design.com/products/
I was really hoping that the iPad 2 was going to have hdmi display capabilities. Maybe in iPad 3? It would certainly make me buy one.
Chris