Music video codes are used to add your favorite music videos to your social networking accounts like Friendster, MySpace, LiveJournal and others. Music videos give visitors and new friends a look into your personality through music and art. Otherwise, you'd have to upload the music video to a server in order to host it, then link your page back to your server. You would have to pay broadcast rights.
Record labels benefit by getting their biggest fans promoting their artists. A fan posting a music video on their blog or social networking account is an endorsement by that fan that says to their friends, "You have to hear the latest music from this artist." Word of mouth is a powerful marketing tool that record labels are constantly looking to recreate.
The more interesting things you have for people to do on your website, the longer they will stay on your website. Using music video codes to create playlists that visitors can watch, can keep them on your site longer. If you have monetized your site with ads, there is a greater chance of them clicking on one of your affiliate sponsor ads the longer they remain on your website.