As a promo, this is pretty nice.
I'm actually still playing through Ys IV, so I cannot comment on the story much. it looks like they got the same folks to do this as they did with Ys 2, and it looks outstanding. I love the way the characters look as well as the animation. Sad they did not make this into an anime, but it's a cool video nonetheless. This video is available on Youtube, so take a look at it when you can. It's only 3 minutes.
Oh and the music? Easy 10. The Ys IV soundtrack always bangs.