Like Zophar said this is old. My friend owns final mix, but unfortunately for him it wont work on his PS2 even though he has the slide card and boot disc. So he let me borrow it a long time ago and I got to experience it first hand. As many of you assume the EM to be hard based off of that footage, well then you are correct he is very hard even on the easiest difficulty setting.
However if you think that Sephiroth is harder than the EM then you would be supreamely wrong, for the EM is more difficult. The ability that many of you are refering to that allows the player to come back from death is the Tinker bell summon. When you summon tinker bell she constantly heals you and when you die she brings you back to life instantly as if you never died then she dissappears and you are unable to use her the rest of the battle. Also there is a new ability exclusive to final mix called "Leaf Veil" This ability allows Sora to heal without taking damage. As you might of guessed this ability comes in handy when you are on the verge of death, however there are times where it doesn't help. Like the eletrical attack that the EM used against Sora in the video clip.
Anyways once you learn his pattern on easy, and Normal mode he becomes easier, especially in proud mode which is the most difficult mode. When I first played it I kept getting my butt whooped by the EM. I had to use the "Diamond Dust" keyblade/keychain to beat Sephiroth to get the "One-Winged Angel" to beat the EM. After that I've been able to beat him with the greatest of ease. Even with the kingdom key; But using the kingdom key at a low level isn't very helpful and it take's a long time to beat him. If I were at level 100 then it would take just as much time to beat him with the kingdom key as it does with Ultima weapon.
Enough of my rambling about this though.
To sum it all up This is old. EM is hard if you have no skill or refrane from continuos playing of the game. KHU, and Soras domain have downloadable videos of FM cutscenes. Almost all of the major KH2 sites have pictures of this battle including this site. If you haven't beaten KH yet I hate to bust your bubble, but if you are under the impression that you will get to fight the EM in the american release of KH well you wont get the chance to because the EM is a Final mix Exclusive boss battle. KHfinal mix was only released in Japan, and it's never coming to America or Europe, especially considering that it's been out for almost 2-3 years. KHFM is the American game with japanese subtitles and extra boss fights, abilities, and enemies which is why the games voice overs are in english.
Here are a couple of screen shots for those of you who are to lazzy to go search for them yourself.
http://www.khinsider.com/gallery/img279.htm
http://www.khinsider.com/gallery/img280.htm
http://www.khinsider.com/gallery/img292.htm
http://www.khinsider.com/gallery/img281.htm
http://www.khinsider.com/gallery/img289.htm
http://www.khinsider.com/gallery/img290.htm
http://www.khinsider.com/gallery/img288.htm
If you want the good stuff look for it yourself.
