Thanks
I did hear that Eminence did release a CD of the event in very limited numbers a couple of years ago, but you had to buy it direct through their website. Maybe if worse came to worst you could try converting or ripping the audio from that Youtube video, but it would be in low quality naturally.
Incidentally, the version of One-Winged Angel they performed was identical in every way to the orchestrated version on the Japanese FFVII Reunion album.