Do you know mate I spent at least 30 minutes doing the same corridor walk over and over,on one occasion I managed to go in the door that was slightly ajar which all of a sudden appeared open.
I'm really not sure how you actually progress in this PT demo if I'm honest and no I didn't finish it ?
There is little in the way of a intro to what the buttons do and as far as I'm concerned you only use a Zoom function to look at things and this dictates how far you progress.
Some spooky Ghost killed me once and since you mentioned it I must revisit it and try and complete it,how long is the demo giraffe .....