which one are you using?Wow. That is an impressive video. I am using a screen protector but from the looks of the tests in the video, I may not need one. I will keep mine on tho because I don't notice any interference with the touch screen so better safe than sorry here too I guess.
I think it depends on who has the phone - I think that many people could probably get away without a screen protector and be fine. In fact I read somewhere that Motorola does not recommend using a screen protector. However, I have a screen protector on mine but it is very likely my Droid could end up in my pocket with keys rubbing against it(which could potentially be more force applied than he was puting on it) or it could be in my pocket rubbing up against a small flashlight I carry or even a piece of 100 grit sandpaper if I am doing some work.
So I choose to be better safe than sorry.