Haven't looked to see if true.pretty cool is so! Psychological Fact- When a person cries and the first drop of tears comes from the right eye, it’s from happiness. But when the first tear is from the left, it is pain.
This right here, explains the whole scene when Harry dances with Hermione. It's actually one scene that wasn't in the book that I absolutely loved in the movie, 'cause it showed how much Harry really cares about Hermione as one of his best friends.