More info
Seems a rather odd post. 'Fuel tank selector behind us' what is aircraft type please?
'Instructor did as as emergency landing exercise ' shutting off the fuel is not going to stop the engine immediately, if you were in the landing pattern it could have stopped very inconveniently at low level.
'I noticed the propellor had stopped' thought you would have noticed the engine spluttering to a stop before that.
Looking forward to the vid