What they don't show is how this idiocy interfaces with the aircraft aisle(s). If there's still only one aisle, it is presumably at the floor level of the lower seats. If that's true, how do the passengers on the upper level reach their seats? If there are separate aisles, will passengers have to crawl to their seats?

I believe most countries have laws specifying that, in the event of an emergency, the aircraft must be capable of offloading all its occupants in some small interval of time. Can you picture what an emergency evacuation of this human cargo craft would look like?