Why Not Pandora?

I guess I'm a little out of the loop and didn't realize people still made music videos, so I was pleasantly surprised to see that many of my faves were on Youtube. Even more surprising was that, for some at least, a link pops up at the beginning that will take you to Amazon so you can buy the mp3.
Having just done our group project on Pandora the immediate question I asked myself was why they don't link to the video. I mean - I know that's a whole other hot mess - but it seems like if they had such a feature they could guarantee more eyeballs will be on the page, which in turn would mean they may be able to ask more for these run-of-site display ads. I use Pandora a lot, and it seems like they end up selling their remnant space through DoubleClick quite often. I am sure that's why they had to start inserting the audio ads. Just an idea...