Of course that scratched it! It would be ridiculous to expect otherwise. Certainly Gorilla glass is a wonderful invention by Corning and makes a screen way more scratch resistant than the early days of the plastic screens on our Treo's. But there're many everyday situations and items in our pockets that can have sandy grit on it that will easily scratch the gorilla glass.
Though I suppose it could be a "doctored" video, Zagg's own video demonstration of their product shows a person using their keys to scratch an iPad 2's screen and the scratches are very very noticeable before they put the shield on and do the same demonstration. Do you think they're doing false advertising there with that video?
Thanks for sharing your personal experience with an iPad in the sandbox. I was hoping someone else would share proof of what I know to be the case in my experience as well.
One statement in support of your claims doesn't a majority make (not that popular votes prove jack). Also, the fact that some scratches rubbed out sounds strangely curious to me. I wonder how the fact that I practically never get sand on my fingers is supposed to factor into this equation? Oh, I know...save my money on a useless screen protector and spend it on something else!