After watching the programme on Channel 4 this evening, I was wondering how these people get away with it all the time, after confessing and being seen on camera - surely that evidence must go against them so that they are then unable to plead not guilty.
They dont get away with it all the time, the footage is very often used to get a conviction. Sometimes they do get away with it, possibly because the footage is inadmissible as evidence for some reason or another or the image isnt clear enough to convict anyone.