Google announced a new way to monetize video content on Youtube. YouTube users will have a new "click-to-buy" option to purchase music and games. Click-to-buy links are non-obtrusive retail links, placed on the watch page beneath the video with the other community features.
Google is getting started by embedding iTunes and Amazon.com links on videos from companies like EMI Music, and providing Amazon.com product links to the newly-released video game Spore on videos from Electronic Arts.
These retail links are being gradually added to the library of music videos and are currently only available to users in the United States, but the goal is to slowly but surely expand the program to additional content and product partners, as well as international users.

This is possibly a more viable way for Youtube to make money. Advertising embedded inside videos is still not solved.
Via the official Google blog. On this Spore Video you can see an Amazon link in action.