Hey! Go to the Options, then go to Extras. While you're there, press L1+R1 (on PC it should be Q+E) and you'll be taken to Hidden Extras. Most stuff is locked but you can unlock all of it if you get a good enough score at the end of the demo. :)
Oh and to make the shoulder view work, you need to hold the "look" button. (I think that's L2 on gamepad, on PC it's Alt)