Hmm... It actually looks like you are applying pressure to the screen when it jumps like that?
Like, the first time it jumps back to where you started, your middle finger had come down and appears to have put pressure on the upper right corner of the display, which might explain why it suddenly went back at least that first time.
In fact, throughout most of this demonstration, there appears to be fingers applying pressure elsewhere on the body as well. Could that be a part of it?
Personally, I've been trying one for a couple of weeks (a boost model that has been deactivated) and have not noticed this happening. When I heard about it here, I tried to recreate it. I guess I can see it sometimes happening and being annoying, but I never saw it happen on its own until then.
Screen flicks and Swype work as expected according to the way I always use them (phone held in one hand, finger on other hand making contact with the display. Never any pressure applied to housing. I learned the hard way that keyboard housing devices can be delicate in the past).