If you want to unlock Salad Days with Pox, pause the game and go to the "Archives" area. Now you have to hold down L3 while you enter the code you see below:
X, Square, Triangle, Circle, Square, Circle, Triangle, X, X.
To unlock Hidden movie, you have to pause the game and select the "Movie" option. Now, hold L3 and press:
X, Square, Triangle, Circle, Square, Circle, Triangle, X, X.