On amplify.ph, people can download music for free in exchange for watching a video ad. The revenue paid for by the advertiser is shared between the site and the artist downloaded.
When the user clicks the download, a quick video ad appears, when the ad finishes, the download starts. The ad must be completed for the user to download, and the advertiser is only charged when the ad is completed and a song downloaded.
This way, the fan gets the music for free, the ad is completed, and the band still gets compensated: everybody wins!