I watched the video on YouTube, and I'll use the comment I put on there for this picture as well. Ahem:...OH. MY. GOSH. I have no idea who in the world they were nor what was going on, BUT THAT WAS NONETHELESS AMAZING!!! The costumes were especially fantastic!
wait... I just read the first 3 books... this looks like something that would happen later in a series... so let's say Tsubasa is my best guess... :/ sorry if I'm wrong, but it IS a good watch/read, so you should :3