[Video] 2009 in Pictures. YouTube Copyright Claim Against Licensed Music. It's OK.

YouTube just sent me a Copyright notice related to the above video:

Dear stevegarfield, Your video "2009 in Pictures", may have content that is owned or licensed by WMG, but it’s still available on YouTube! In some cases, ads may appear next to it. This claim is not penalizing your account status. Visit your Copyright Notice page for more details on the policy applied to your video. Sincerely, - The YouTube Team

When I click through the link provided I end up here:

My choices are:

1. Acknowledge
2. I believe this copyright claim is not valid.

In this case I've used Animoto to create the video, which has licensed the music from WMG. So I acknowledge that I am using copyrighted music, and that ads may appear next to my video.

Good thing "This claim does not affect my account status" because there's no where for me to provide an explanation that although the copyright claim is valid, I have permission to use the music.

Confusing!