Music videos are filmed artistic visions of musician's song. Trying to find an actual link between song and video, however, is impossible and you will get an aneurysm if you try.
There is none.
However, some people will try and say things like the following:
Many famous directors made their start with music videos, like Martin Scorsese, who first directed Michael Jackson's "Bad" video and went on to make Oscar-caliber films, and Marcus Nispel, who directed Janet Jackson's "Runaway" video and led him to make... the Friday the 13th remake. You can't win them all.
MTV and VH1 made their fame by airing music videos 24-hours day. For some unexplicable reason, this bothered people, who criticized the network for being callous, pandering, and providing a terrible influence to the youth. Unlike now, showing such quality televison programming such as Paris Hilton's My New BFF and Cribs. If that's TOO adult for you, then Teen Cribs is right up your alley.
Music videos also introduced people to different varities of music, such as rock, rap, alternative, electronica, R&B, and pop. With so much new and exciting music available to them, by the time iPods and music players came around, people eagerly began downloading classic, non-videoed songs instead.