Restore my music lib from Apple TV
I was able to restore my iTunes Music library from the Apple TV.
I use an external USB hard disk connected with my Apple TV (and ATV-Flash software) to have more disk space. All music files are on this external disk.
My iTunes library, with which this Apple TV was syncing, was stored on a Time Capsule. Not a good idea, because I got the dreaded "Disk Needs Repair" error from the Time Capsule. I also had no backup of this iTunes library (bad idea no. 2), because I assumed that the Apple TV contained an exact copy of my library.
Well, it turns out it does, although it is stored a bit differently. Instead of storing it with the Artist's name, Album name, Song name structure (e.g. /Deep Purple/In Rock/Child In Time.m4a), it uses something different, like /Media Files/F01/T87YH4.m4a.
What I did was connecting the external hard disk to my Macbook. In iTunes I then created a new library and by using File -> Add to Library, I selected the Media Files directory on the external hard drive of my Apple TV and it imported everything, with the correct Artist name, Album name, etc. It also seems to still contain everything I added, like Grouping and Comments, Cover Art etc.
If you don't have an external hard disk connected to your Apple TV, I suggest you do and buy ATVFlash. It will add some cool features to your Apple TV and a lot more storage space. When connecting the external drive for the first time, all the Apple TV data that was on the internal drive is first copied to the external one. After this you can disconnect it and do the iTunes library restore as explained above.
Maybe this was obvious to others, maybe not. Just thought I'd share it with you. Maybe it can help you out when you are tearing your hair out because you lost 200 GB of music...