Purpose of music promo videos

The main purpose of music videos is promotion and publicity in order to making money which means generating high sales. It promotes the artist's single or album , persuading the audience to buy and download the artists music.

Another reason is product placement where a product is advertised in a video. A good example of this is  Mike WiLL Made - 23 ft Miley Cyrus , Wiz Khalifa , Juicy J 

Mike WiLL Made-It - 23 (Explicit) ft. Miley Cyrus, Wiz Khalifa, Juicy J in which they advertise a number of things or example the 'beats pills' which is also seen in other video's such as 'Miley cyrus w cant stop'. Another product shown is  the iPhone and Jordan shoes which are a main theme in the song. 

Synergy

A great amount of this is videos featuring films as a way of promoting.This is because if they like the song and they watch the music video and find that it is a soundtrack to a film, they may want to go and watch that film. It can also be vice versa if they like the film and the music is played in it, they may want to go ahead and listen to more. For example the band wet wet wet's soundtrack for the film four weddings and a funeral that features clips from the film. 

Mirrors are used often in the video to show images of the film. Therefore it conforms to Goodwin's theory there is also the use of editing to the beat of the music.