I'm saying that they're sacrificing an instantly replacable battery for a clean underside, yes - and I've seen the video. The two hours extra is most likely because battery company X has a slightly improved product, using square cells instead of round ones is hardly revolutionary either
The 17" model looks no different. It looks pretty feasible to have the exact same pack of cells fit in the laptop and still have it removable - People seemed impressed at the marketed runtime of that, but all it seemed to be was a large laptop (without dual hd/etc features of similar products) with the extra space used up with a large battery pack.
I'm sorry but your points make no sense. Yes it's not a big revolution tu use square cells but it's also Li-Polymer instead of Li-Ion like most laptops out there today. It gives you 1000x charges vs 300-350 charges you get in a conventional battery. That's the main reason Apple decided to make an integrated battery. If you're going to change your battery in 1-2 years then integrated makes no sense, but if you can extend that period to 3-4 years then suddenly you would not need to change the battery on your laptop for it's lifetime.
It would be near impossible to fill the exact same amount of cells in an removable battery because of the frame, hinges, latches etc it uses. I thought that was clearly stated in the battery tech video. Engineering is not only about the best of the best tech, it's also about feasibility. Sure Apple could have spent billions for a compacted battery tech to fit the same capacity batteries in a removable design but that would have made the battery pack far more expensive due to the complicated process and R&D.