Okay, something is not quite right with that video. I am not saying it is not sapphire crystal, when he tapped on it with the knife it did not sound right, It had dull sound. I have my sapphire crystal watch and just did the same thing and it tings like a crystal wine glass, verse a dull dud of a plane water glass. Crystal structures have a distinct sound that make so it not sounding as if it is pure sapphire crystal. They much be doing something else here.
Maybe apple is depositing sapphire crystal onto gorilla glass or something similar Thus the reason it is not scratching and it has a dull sound.
I don't know anything about Sapphire glass, but just going by the video's that you linked to it should produce a dull thud. Perhaps someone just told you that your watch was sapphire?