I don't think you can use CCTV footage in evidence unless CCTV warning signs are put up.
As someone said, think about your neighbours, I would want someone looking in my house, and I doub't you wouldn't ether.
I have put 3 dummy cameras up and 2 signs, and it has worked, but people still steal, fight, and run riot despite cameras recording them...just look at all the programs on TV showing these fools !!.
I know there are cameras which you can view through the TV, which are great for identifying vistors.
My advice - Stick with the cameras, but think anbout the outcome, if you view a crime in progress, do you run out and risk your life,or call the Police.
ALWAYS think safety and ALWAYS think Knife...A life is worth more than a lawnmower or a kids bike.
Good Luck