First, if you haven't seen the video, watch:
Now ... the rest of the story:
Last week the world watched in wonder as Jill Peterson and Kevin Heinz's wedding party transformed a familiar and predictable tradition into something spontaneous and just flat-out fun. The video, set to R&B star Chris Brown's hypnotic dance jam "Forever," became an overnight sensation, accumulating more than 10 million views on YouTube in less than one week. But as with all great YouTube videos, there's more to this story than simple view counts.
At YouTube, we have sophisticated content management tools in place to help rights holders control their content on our site. The rights holders for "Forever" used these tools to claim and monetize the song, as well as to start running Click-to-Buy links over the video, giving viewers the opportunity to purchase the music track on Amazon and iTunes. As a result, the rights holders were able to capitalize on the massive wave of popularity generated by "JK Wedding Entrance Dance" — in the last week, searches for "Chris Brown Forever" on YouTube have skyrocketed, making it one of the most popular queries on the site:
It continues from there.
Basically the bottom line is:
1) Give people a fast, affordable, and easy way to buy something now now now and they'll do so.
2) Don't be stupid and run to issue a DMCA Takedown notice!