I believe that the song is really about a baptism and the beauty it can bring into your eyes after it is done.
But the video brings a whole different meaning into my head. In the video, the old man represents God, and the bugs are, well, the not so pretty people of this world. He's putting the diamonds, or the brightest of beauty, inside them to keep them safe when the people come in. The people represent the Devil and they are trying to find the beauty to turn it evil. But as does everyone else in the world today, they overlook the outside of the bugs, not even thinking they could be there. This proves the point that most mean people look at the outside, not the inner beauty.
So, I think. "Beauty really does lie within." :)