I think this only works on WINDOWS Computers but im not sure.

After installing the game go to Main Drive:Program filesLucasArtsStar Wars republic CommandoGame dataMovies.

For:

A) A music vedio go to ExtrasAsh
B) Concept Art go to ExtrasConcept
C) About Foley Sound effects go to ExtrasFoly
D) interview with Temuera Morrison go to ExtrasInterview
E) A short movie about Spec. Ops go to ExtrasTraini

Also here are 3 things you can't unlock on the game:-
The background to the menu ---- Menu_BG
The LucasArts intro that you see when you start the game ---- LECIntro. I dont know why its called this!
The NVIDIA intro that you also see at the start of the game ---- NVIDIAIntro