Here: http://www.jamendo.com/en/creativecommons

If you are going to upload the videos on youtube, then only the "Attribution" albums should be used because all the other licensed-music there either does not allow commercial usage (youtube is commercial, even if you don't get paid), or share-alike SA-licensed albums requires you license your videos under the same license, or the ND non-derivatives albums don't allow you to combine that music with any video. So, if youtube is in your future, only use music from these 147 albums that are marked as "Attribution" only. You will have to give credit to the artist as I do in my credit roll here: http://vimeo.com/366681

If you are never going to upload anywhere and only keep the videos at home with friends and family, then any album in that list is good except the ones that are marked "NoDerivs" (because non-derivative songs don't allow the combination to video). There are about 5,000 albums to download there for free that are not non-derivs.

Personally, I would recommend you only go with these Creative Commons albums, not commercial music, or "free" music from sites with shady licenses. Creative Commons licenses have been ported worldwide and it's your best bet for a fair and clearly described usage. Also, read here to understand the differences between the various Creative Commons licenses. I promise, they are written in plain english, not legalese.
http://creativecommons.org/about/licenses/meet-the-licenses