Hi JM26,
Don't worry, I think it's not that you are not better or anything than the rest of the candidates.. just that pressure might have taken control. I think you had over-stressed yourself and hence got STUNNED by their questions. Who knows, there may be much more better opportunities out there awaiting for you in the days to come!...
Give yourself a pat on the shoulder for making it to the second round dude....
Good luck and thanks for sharing with us your experiences!