first of all I know this is all make believe...but still the brits are portrayed as so arrogant they think if it aint british then it aint nothing, they also think the rest of the world like the colonies or australia or whatever are mere children and use primitive magic...but in their arrogance and dumbing down over the millenumum by power hungry ministers and headmasters they have lost contact with all the other powerful magic users in the world to the point they either think they are myths, legends or fairy tales! so snape wondering how harry did these things, his mind just cant seem to conprehend or grasp the ideal that there are other more advanced magic wielders in the world other than what he knows in his limited way! there did I explain it well...great story as always!