Three years. That's what it took Matt Perren to make the lip-sync video you can see above, a time-lapse in which he moved his mouth every day to match the phonemes from Queen's Don't Stop Me Now, then took a photo. I don't know if he is a genius or a mad kid, but I love him.
And yes, the technique is also used in music videos. But those are made in a very short time, not during the course of three years. Like this one by SMWfilms:
In Matt's case, however, the time-lapse effect is not the dramatic changes in background or clothes. It's his face and his entire body that changes dramatically.