Not scripted? I looked at the scripts. It's about as scripted as you can get. It's about on par with a MoH:AA or CoD "movie" level like DDAY or Stalingrad, which seems like an odd choice for a demo level given that the MoH:AA and CoD demos were all "normal" gameplay levels.
Definitely flies in the face of their "unscripted" claims. Load up MOHPA_demo_section01.scr and see for yourself. Here are some excerpts:
//Camp is dead start the timer for the next camp battle to spawn
if( local.trigger != NIL && local.trigger != NULL )
//Trigger the camp attack. This is safe because the trigger is monitored in a thread that can only happen one time.
// Wait for their to be only two guys left, then wait n seconds and start the pilot gag.
// This turns on a trigger for the squad to rally outside the building
// The first plane is destroyed when the player walks out the door
The thing that is kind of boggling is that so much of the "logic" for the level is in the script for that level, like level specific script for each plane and each pilot, which makes it a lot less surprising that it's taken 85 people three years to make 25 levels.