Shireslueth, for reasons I don't understand you persist in ignoring the CCTV at the back of the Cornhill shopping center.
That (not the cam on Greenwoods) defines the northern boundary of the area Corrie could have moved around undetected, and also the area they can see cars exit and enter. This was clarified for us in the update on the 30th December, and expanded upon a week or so later when Nicola shared the "walkaround" video. That's why the family, and it seems the police, believe Corrie could not have left on foot.
http://www.dailymail.co.uk/news/article-4118636/Was-RAF-man-vanished-air-abducted-terrorists.html
There's a few obvious riders:
- This is only true up to 4pm on the Saturday so far, that we know.
- There's apparently a small chance, if someone was deliberately avoiding cameras, the could "escape"
But just to reiterate, the fact that corrie could have evaded the Greenwoods cam does
not imply he could leave the area.