That makes sense to me, and I can see that logically. I tend to think that controlling the motion might not be enough to tell these mechanisms in our brain that everything is OK. I still think the brain knows that the eyes see one thing and the ears feel something else, and doesn't really care that the hands are telling it "I'm pressing the yaw button, so don't worry, eyes and ears."

But I'll have to see. I don't think I got very queasy when I watched that Walken video. I wouldn't be surprised if it gets worse after more time (it was a fairly short video with lots of cuts), but I can tell you that I can't get through the first training level of Portal without stopping for 30 minutes. It's awful.

Part of it might be concentration. If I know I don't need to focus on making that jump/hitting that target/throwing that switch, perhaps I'm able to sit back and watch it with a spectator's view.

*edit*

Okay, I'm completely wrong. I only made it through half of this video that's been going around the web recently.

I need to go lie down now...