Maybe they simply put all the cutscenes from Last Mission together, removing the gameplay aspect from it.
Last Mission was about as good a sequel to FFX-2 as you could get. I mean, in X-2 the player's choices really matter and there's no real canon. In Last Mission, depending on the choices the player made during X-2, the cutscenes alter. If you don't get the good ending, Yuna won't talk about being together with Tidus.
What I'd really like to see is a cutscene between X and X-2 that establishes the Coliseum. It's an awesome gameplay feature but - like most International additions in FF - makes no sense story-wise.