Yes I can. And wait, you haven't even seen the show (which I'm guessing isn't bound by what happened in the [non-hit, as I recall] movie). My provisional explanation for the library is that Buffy, Willow, and Xander aren't aware yet of the extent to which they don't share the same reality as other students; but this would mean that somehow Xander and Willow were already "chosen" in some way. I also think it's possible that Xander may not altogether be what he seems (to us, to Buffy, perhaps to himself). But maybe not.