I like in that old video how big some of the rooms are, it's a lot like POTC or the final room in Splash. In reality I don't think it will be like that just because of the show buildings medium size. I also like how the ride vehicle drops under the sea. I'm not sure how this will turn out. The show building does have a large cieling height but maybe not enough to tier the ride over itself.
I could though, see a load and unload area on the second level with the que underneath.
I'm also curious about the ride vehicles themsleves. In the drawing they show the clamobiles which is a omnimover system like in HM. But they use this in the finding nemo ride in Epcot so I don't see it being used in the MK version of LM so why in DCA?