For my money, the purpose of a music video is to get you to buy a song. The basic idea is that you want to watch the video, hopefully several times, and thus either like the song (either from the start or through repetition) or associate the song with the cool video and thus want to buy it to "relive" the coolness of the video.
A lot of bands (or their record companies) seem to have missed this basic premise. They throw the band up in front of a microphone, or have them sitting in a car and singing to the camera, etc, and this is really only the barest cut above radio.
OK Go is one band that consistently seems to "get it". Their
video for "Here It Goes Again" (the one with them on treadmills) made me watch it repeatedly and eventually buy the song. Their latest release is equally watchable (and the song is already growing on me).
Click to view
Side comment on the video: Man, that is one unafraid goose at their feet at the end of the video there.