[QUOTE] I think Ryanair need to adopt an announcement like Easyjet have, when a few minutes after take off, the purser announces something along the lines of "Very shortly, the cabin crew will be released from their seats, please continue to observe the fasten seatbelt sign until the captain has switched it off". [/QUOTE]
They already do consistently by crew announcement as soon as they're released from their seats. It's also enforced in the safety demo and on the seat-back safety instructions that quite honestly, very few people will actually look at despite it being plastered right in front of your face. Equally if anybody does stand up with the seatbelt signs on, especially around taxi, takeoff or landing they'll instruct them to return to their seats. Other than physical enforcement what else can they really do? If anybody causes a fuss or refuses to comply then that's going towards disruptive behavior territory and there's a whole different protocol for that.
Saying that I've definitely observed a behavior by Ryanair crew to keep the seatbelt signs on during trolley service, which I feel is nothing more than a deterrent to people getting up and using the toilet whilst the trolley is in the aisle, rather than for any particular safety reason.