Kingdom Hearts II Final Mix

[Nightshade X]

I would wager that this is a prequel.

The following is probably just me overstating: In the video, King Mickey is wielding the Star Seeker, the same keyblade that is given to Sora after he visits Yen Sid. I see that as a kind of a sign of Mickey's apprenticeship to Yen Sid, which would nod to the statements made by Donald that Mickey trained under Yen Sid.