I like how introspective and almost intimate the music is for this moment, definitely focuses more of the two characters and the moment they're sharing together, rather than the overall drama of what's happening. I also like the instrumentation you picked, the piano is especially effective especially towards the very end :)

This is suitably calm for a death scene.  My concern is maybe it should sound graver and sadder a little when she is stumbling to her knees in the first few seconds, I got this impression there were kind of four, five distinct stages to the video, like Xion vitally communicating instructions etc before she passes, etc.  That was the only thing was it was a little too uniform without some ups/downs for the segments.

That said, I thoroughly enjoyed it.

Really nice piece. I loved how calming and soothing it was. I went for a dramatic and tragic sound for mine, so I really like how your piece almost goes in the entirely opposite direction thematically. It sounds to me like she has accepted her death with peace and grace, and I love how you managed that.

Nice job on the music! This is a good demonstration of how one should play melody and chords at the same time on piano.

I would recommend using REAPER to get started if you want to be able to compose along with a video.