Looking at the model, I assume that the people board their seats and then the entire assembly moves forward towards the screen.
Again, I am taking this back to the thought behind modeling this after the movie. Following the ascent up into the floating mountains, Jake battles one of the ikran (or banshee) to join with it (ewwww) and make 'the bond' - that's what the hipsters call it on Pandora these days. Anyway, once that happens, the rider is to immediately take the first flight. In that scene, Jake and his banshee dive over the cliff and plummet straight down the mountain cliff face, well above the moon's surface. Combining that with the design of the simulator, that could be recreated almost perfectly. Once everyone is strapped in, the rows of people lunge towards the screen, simulating the banshee running towards the cliff edge and immediately going into a dive down the face of a floating mountain.
Again, as I stated in an earlier post, the queue for this could be amazingly detailed to appear like you are ascending a floating mountain. You then board the ride vehicle - your own banshee. The vehicle then thrusts forward and you are now diving down the face of a floating mountain.
I really think that this ride has the opportunity to simply blow Soarin' in EPCOT out of the water. A lot will depend on the extent to which it is themed. They could go all out like they have with the other rides in DAK and this entire experience will be mind-blowing as you fly on the back of a banshee through the Floating Mountains and down into the forests of Pandora. To me Soarin' Over California is a nice easy flight. This one most definitely will not be.
What would make it even better is if they had multiple movies divided among the 4 theaters, much like Star Tours in DHS. One could even be dedicated to an extreme experience, probably more to the liking of Cameron since he didn't get his white-knuckle coaster ride (yet
).