It's a common problem: your point-and-shoot camera's microphone picked up nothing but wind while you were at the park shooting a video of people flying kites. The solution? Wipe over the track with music. But putting licensed music over the videos not only requires video editing software, but also the digital rights to publish. YouTube has rolled out a new service called AudioSwap which hopes to quell both of those problems.
To use AudioSwap, just pick a video you've uploaded and browse the provided audio list. You'll get a preview right away, and with the click of a button YouTube will start processing the request. I found with my test video it only took about 30 seconds to show up with the new music, which is far sooner than it would take to manually add music and re-export it in a video editing program.
It will be interesting to see whether YouTube ventures into a paid-for license model, to add new and popular music tracks to videos for a small fee.