doesn't really look like a gamerip, more like different versions of the same songs.. but whatever, you might be able to help.
Ys The Oath in Felghana - Chester Battle - Low Level Challenge (Inferno) - YouTube (
http://www.youtube.com/watch?v=AN6ElyFwEQI)
in the battle against chester, I hear music that's nowhere to be found in this rip. you sure you got everything?
or maybe some music from a different source (game, anime, whatever) was encoded in this battle? if you keep listening, at the end of the battle there's a short piano session that doesn't seem like part of the previous song (still in-battle. you'll have to watch the whole video to understand what I mean). however, it doesn't seem like a manipulation to me. it looks like legit music from the game. still, can't find it.
That is most likely installed music by the uploader, the track that plays in the battle with chester in that video is the track U.N. owen is her? remixed, from toudou 6:embodiment of scarlet devil, which is why the song goes quiet at parts, the piano version also comes from toudou, though finding that exact version is tough, as there are more toudou remixes than even final fantasy remixes.
In other words, the music is a game hack into the game or a dubbed over track in the video.
Here's the original version of the song btw:
http://www.youtube.com/watch?v=VIop055eJhU