I have manually burned CDs of the music that we have purchased on the iTunes Music Store, but I wanted another backup, so I looked to Backup 3 to do this. Backup has a "QuickPick" that is supposed to allow you to easily backup all purchased music. This doesn't work for me.
I have moved my iTunes Music library out of my home directory. I did this originally when I was using FileVault, as encrypting all of my music took too long. But even though I am not using FileVault, I still like having the music outside of my home directory, as every user on my laptop can access regardless who is logged in.
It looks like the Backup QuickPick for purchased music only finds the .m4p and .m4v content in your home directory, and nowhere else on the disk. In addition, it is not possible to modify where the QuickPick gathers the list of files.
I am going to attempt to find a Spotlight statement that will find all of the purchased tracks everywhere on the disk.