At the end of the demo, walk out and do the fence glitch... incase you don't know how, equip you knife and slash the first piece of metal off the tank-rack (Yes, I love that gun...)
Now jump up on this... thing, look a little to your right (Don't look too much over there... the demo will end) and hold your crosshair as shown (At least that's what I do...) Jump up on the strange thing holding the fence together (Might take a few tries) and continue to the other corner... by jumping... again...
Jump onto the lamp over there (Now the difficult part is over) and walk across the edge as shown ^^ (Don't look to your left, don't) and so you don't look to your left, use your shadow here to walk the right way... left.
Can you guess what time it is, kids?... Yes! It's time to cross the floodgate! Walk back onto the metal piece behind you as shown in the first pic, jump up on the gate as in the second pic and run across... as in the third pic... BINGO!
Look to your right at this thing holding the building together with the piller.... you're going on top of it! try jumping on top of it, if you miss it entirely... you fail, restart the thing... if as in the second pic, you land just under, you can jump back and try again, when you're up there, crouch under the invisible wall and land down there... do NOT look or walk back... it'll break the game and you will fail...
So walk around here, break some things if you like to and a text will appear at the end... I got a bad pic of it, it says "Collect intel documents to unlock unique content on Killzone.com" but anyways, do NOT and I mean do NOT walk around that corner, the game will break... again... just look around the corner as shown bellow..
Around the corner is the first intel, I'm trying figure a way to get over there, but until now, it's still pretty to look at I guess...