The cool thing about the P.T. demo is it's slightly randomised too. Some of the things that happened in the video I linked, didn't happen in my playthrough, and there's also no general agreement on how to get the phone to ring at the end to trigger the actual reveal trailer -Other than hearing a baby laugh twice.
I had to give up on it though, one part of it involves trying to find a ghost (which if she catches you, kills you) and talking to it via the microphone. This got too much for me eventually and I had difficulty sleeping that night. Not due to it being scary, it was at first, but after a while it just became tedious.