You cant. But, the poster didn't do that at all, didn't even mention the video. The post is short, so its not hard to see that.
My skeptical question would be: how can you set a mission in a genuinely dynamically generated world? For example, you might not even know that a bit of land will exist where you want the mission to begin. But, maybe I'm missing something obvious.
Procedurally generated just means you can create lots of variety; not that you can't generate ahead of time, save it to disk, and even put potentially useful features in the database and then just pick from those when putting together a mission.
My skeptical question would be: how can you set a mission in a genuinely dynamically generated world? For example, you might not even know that a bit of land will exist where you want the mission to begin. But, maybe I'm missing something obvious.