I didn't make it!
I need to know how to make the game screen size smaller or a program that can quickly minimize the screen (alt+tab takes to long).
You could try editing the VideoDefault.com which is in C:\Program Files\EA GAMES\Battlefield Vietnam\Mods\BfVietnam\settings.
Open it with notepad and change renderer.FullScreen from 1 to 0. save and close.
I have no idea if this will work as I have never tried it.