I've seen videos where the voices are done with American accents. How do you access that?

I have the game on CD ROM and from GOG and I've only ever heard the Eastern Europeans, which does make me smile, but...

Oh, you too ^^ ? I just finished it and yes, those voices felt (very !) slighty weird ^^... But I didn't knew there was another version of the game. Where did you find that video ?

I found it on YouTube. There' a few. But I don't know where you get that version from.

I bought the original US release as Codename: Outbreak by Virgin games and bought it again here at GOG and they have the same funny voices.

I have no idea what exact version has those voices but having them as an additional language option would be nice.