It's responding to an item you have

[Depression Moon]

I played FFIX a couple of days ago because I was bored and deciding that I should finally try getting Zidane and Freya's ultimate weapons along with completing the whole chocobo quest. I was also doing the mognet quest too and my venture lead me to the Black Mage Village. I went to the inn and talked to Black Mage standing next to the genome by the phonograph. He said something first that I couldn't remember and then this strange music started to play and the screen went dark and some strange messages appeared on the screen. It might've been before or afterwards, but the mage said something like "It's responding to an you have".

I went back there today and he just said "It's that song again" and it came back. The song was eerie, but beautiful.

WTH was going on?

Edit: Damn, left out "item" in the thread title.