[Shannon Bedford]"I'd be interested to know how the overlap effect is achieved at around 31secs. Is it just cropping? "
It's called rotoscoping.
[Shannon Bedford]"Would the final shot be outdoor green screen?"
You could, but then you'd also need a clean plate to fill the part where the green screen is. That shot at 31 secs would be pretty easy to manually rotoscope so a green screen/keying/backround replacement would take more time.