There is a legal requirement on the Captain to ensure that all of the passengers are suitably briefed, however there is no compulsion on the passenger to listen.
Not quite correct (calling all pilots please read the ANO)
The ANO states that you must obey any reasonable request or order given to you by the commander of an aircraft. What this means is that if the captain orders you to engage in a sexual act in the toilets you may refuse but if he asks you to listen and watch the safety briefing you are obliged by law to do so. ( I have been campaigning for years to get the former request written into law but have been told it is a load of cock)
My opening PA includes this briefing
"The cabin crew will shortly give you a safety briefing please listen and watch and give your full attention to the crew." (That is an order not a request)
Anybody who has not watched the briefing could be gulity of endangering the aircraft as they may slow down an evacuation. It is an offence at anytime to endanger an aircraft.
If a cabin crew member reported to me that xyz passenger had not looked or listened to the briefing technically I cannot fly.