It's been too long since I've seen the outfit in question so I can't really answer it. Do you have a screenshot handy?
If you're talking about an outfit that appeared during a cutscene only the chances are good that you won't be able to get the outfit. This doesn't matter if it was in-game or a pre-rendered video, as the NPCs used in cutscenes aren't always player characters, or "APC" (let's call it Automated or Artificial Player Character) as it's called in-game.
An APC uses character parts that a player can gain access to as they are for all intents and purposes fake players. An NPC doesn't, as they are entirely self-contained models. Cutscenes can use APCs and NPCs (and can possibly even add unique models to APCs), but if it's a unique outfit on an NPC you can't get it. I'm not sure I'm explaining this well but hopefully you understand.
Edit: Oh just read the PM. This outfit:
I'm afraid that's an NPC, not an APC.