I was on a recent flight on CX, I was seated in an exit row, so my personal TV was folded down. The main screen wasn't working properly during the safety demo so the cabin crew came around and pulled up our personal TVs so we could see the demo.
The guy sitting next to me, said that it wasn't necessary, and that he'd flown hundreds of times. The crew said that it was a legal requirement. The man tutted and as soon as the crew went away he folded his TV down again.
Interestingly enough even though he had flown hundreds of times, he didn't know that hand luggage could not be simply left at his feet in an exit row, and seemed very surprised when the same crew member asked him to stow it.