I have the International version and this is a rumour.
I love hearing the things that people come up with...
It's only in New Game Plus apparently. Are you sure? Or is it in the International JAPANESE version, maybe. The video is in Japanese with English voiceover. But then again Tidus and Auron have battle quotes in English.
EDIT:
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
F - CREATURE CREATE & BATTLE SIMULATOR
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
For starters, check out these two guides:
db.gamefaqs.com/console/ps2/file/final_fantasy_x_2_ilm_creature_create.txt
http://db.gamefaqs.com/console/ps2/file/final_fantasy_x_2_ilm_capture.txt
I'll only make a short recap on what Creature Create is (thanks to Kouli)
1. CREATURE CREATE system allows you to capture practically all fiends in
Spira and use them in battle, along with NPCs in the game, like Yaibal,
Lucil, Elma, Nooj, Baralai, Gippal, Trema...
You'd also be surprised to know that some of original FFX cast can be yours
to command: Tidus, Auron, Lulu, Kimahri, Seymour, as well as Aniki/Brother,
Dachi/Buddy, and Strongest Shinra (nope, this is not the normal Shinra,
this is another version of him).
The Creature Create system alone is pretty much worth it. Very fun and
addictive. You capture fiends using different sized items called Pods, then
it's your job to level up creatures and see their Episode Completes. Fiends
you capture, or rather the % of fiends captured, is also shown. When you
EPCOM a fiend, you have the opportunity to release it and view a special
scene - some of them are hilarious, while some are needed to get access to
new fiends for capturing.
There are 184 fiends to be captured in the Creature Create mode.
Once you complete 100% of all fiends, and you view Shinra's ending, you're
presented with an option of creating New Game Plus data.
2. BATTLE TOURNAMENT is the place where you can train your creatures or level
them up in order to gain Story Levels and possible Episode Completes for
them. There's 10 different tournaments, which allow you to fight lot of
fiends and NPCs. Needless to say, Trema and Paragon are among them. The
final boss of Last Mission also appears in one of Battle cups - its name is
MAJOR NUMERUS.
Figting in Battle Cups is the only way to get Tidus, Auron, Seymour and
Strongest Shinra to join your party.
3. For any other information please refer to two guides I linked to above.
This document lists differences and extras, not detailed information on the
two features.
Ngr, you may claim to have the game, but for some reason I believe this over you.
Also, what they claim about "a different Shinra" seems to match with the video, cause in one of the parts I've watched so far in the video I saw Shinra's face in the menu screen and was like WTF? It looked kind of like Yojimbo's head.
This FAQ and the video are from two different sources and seem to match with the Shinra thing and other stuff as well, but if you really have the game Ngr, do you think it's possible that you might have not known about this? I suggest checking out Gamefaqs because there is actually more than one FAQ that states this. A bunch of different FAQs lying about the same thing and having a whole section devoted to that lie is quite a large claim.