So much of what they were doing required multiple high resolution cameras, to be able to track the craft's aboslute position in three dimensions. Meaning that most of those stunts could only be done in a room specially built for that purpose. I wouldn't be surprised if they also had to make sure the room was without any breeze or draft, so that wind couldn't affect the behavior either.

What would make a demo like that a lot more impressive is if copters could do those stunts outdoors, in weather, without needing a set of remote cameras to tell them where they are. Maybe someday there could be internal sensors in those kinds of copters that would have enough detail to do that.