I kind of look at music videos as a way of comparing a lot of other peacock feather activity in culture - a lot of 'look at my fitness indicators, they be fit!' indicators. I say it in a mocking way but with some affection (it's best to keep a sense of humor about things you care for, I think)
Okay, if I were to plot this in tribal terms though - ie, to think where would the behavior be applicable if we were to go back ten thousand years - well, to me dancing around and displaying would be something you do when you have a very solid food supply. Indeed, in order to show you have a very solid food supply (as dancing requires calories, so it's a fairly strong proof demonstration - the starving don't dance).In this context I'd consider this a reasonably functional behavior, myself.
So we can take it in the tribal context that
1. The dancer has a good food supply that they control - enough that they can burn calories on dancing
2. They are dancing - indeed, dancing about their food supply control
So, back to music videos. Taking it to be fitness display behavior and that's why the music and dance is worth a damn to watch. But what about number 1?
1. ?
2. They are dancing and singing
Okay, so maybe you like the band who is in the music video. Okay, so how do they get their food - how do they control their food supply? What is fit about them?
Apart from appearing fit so you buy their CD's and they use that money to buy food and mansions/more display stuff. Which, you realise, has nothing to do with actually being fit - it just has to do with triggering your sense of fitness when that's not the situation at all.
So meaning floats, sheered away from it's anchor #1, that rested in owning a food supply.