Why does music have to relate to the music video?

Answer 1

Actually it is the music that is made before the music video so your real question should be why does the music video have to relate to the music. The answer to your question though is because if it didn't relate it wouldn't make any sense at all. They want to kind of give you the feel of the song that is the whole point of a music video.

Some Music Videos don't really relate to the music at all.