rmcdonal,
When the crew say leave your seatbelts on while seated there is probably a good reason for it.
If it's good enough for the professionals to do it (leave their belts on and fastened), then it's good enough for me the punter SLF in the cheap seats.
Maybe the outcome of this will be a forceful demand for SLF to put down their papers and PAY ATTENTION to the safety video / demo, as well.