so this is used only after the song gets blocked?
or even if there is a copyright claim, but the song is not blocked yet, do i still have to put that in?
Yes, you use it after a song is blocked. Because you 'don't agree' that they've blocked you the music track :D
If there's a copyright claim but the music is still avaible, I'd recommend you not to do anything, probably the song won't be blocked. When the owner of the song is e.g. Sony Music Entertainment, they only tell you that this song belongs to them but it's still avaible.
