Doesn't this kind of make a mock of the Captains, Cabin Crews and video statements for passengers to " remain seated and keep their seatbelts fastened at all times even when the seat belt sign is turned off as a safety precaution against the unexpected etc etc"
I think that is a slight mis-quote. The one I hear most often is:
"The Captain has now turned off the Fasten Seatbelt sign. However, we would like to remind you to keep your seatbelt fastened at all times when seated."
A small but important difference.