you could call borat the first dynamically scripted movie - ever. the film had a basic plot line and for each scene, the producers, director and borat knew beforehand at least part of what they wanted to accomplish in the scene in order to progress the story. but except for pamela anderson and the prostitute (and obviously borat and azamat, that goes without saying) all the participants were real live people who thought they were being filmed for a documentary. most of the plot progression was made through either narration or scenes that only the actors played in, not so much in the scenes with real people.
for example (of which baron-cohen detailed in a recent interview), the scene at the church was used in the plot to show how borat moved from being depressed to being reinvigorated. nobody in the church knew about that, all they knew is that borat is someone who isin the middle of a crisis and they just played their usual voodoo on him.