That kind of spike in traffic across partnered sites is a huge selling point for YouTube. It makes it much more advantageous for new partners to come on board. Aside from music labels, other industries like the motion picture studios, video game creators, TV shows, and more will shortly have the ability to promote products within videos. Imagine watching a review of an external hard dive on YouTube and then clicking "Buy It" somewhere in the middle of the video. **It's purely instant gratification**—and people love it. I wouldn't be surprised if by next year we have the ability to hover over a product in a video and be shown a dynamic menu that lets you (with one click) buy the product. YouTube is killing it, for themselves and their partners. Smart product placement and click-to-buy options will continue to evolve and keep them on top of the online video market. The market will learn from YouTube's example and adapt, ultimately perfecting the feature and burning another hole in your pocket.
[W]hen Monty Python launched their channel in November, [...]their DVDs also quickly climbed to No. 2 on Amazon's Movies & TV bestsellers list, with increased sales of 23,000 percent.—YouTube's Blog