Whether it's a safety video or a live demo, once the novelty has worn off (the passengers have traveled by air more than twice), it's just a case of familiarity breeding contempt.
Liven it up, add some humor, or that cringeworthy Wayne Brady style rap version that's doing the youtube rounds, and the novelty of that will wear off after you've heard it a couple of times.
If crew were enterprising enough to come up with an original method of conveying the info each flight, you might get all pax paying attention each time, but by the time you're on you're ninth sector you'll be reduced to plagiarizing Monty Python (We are no longer the Knights who say Nee, we are the Knights who say "Open your seatbelts come this this way, jump and slide, no you can't have another rum and coke").
Scare tactics won't work, telling people they will die if they don't remember how to tie a neat double bow at their side with the life vest straps will cost the airline a stack, and again the novelty will wear off quickly.
Pop quizzes may be an option. Offer frequent flier miles to anyone who can tell the crew how many emergency exits there are or demonstrate how to put on a life jacket 3 hours after the demo. Alternatively, deny drink/meal service to anyone who can't do these. (No sir, the brace position is head between your OWN knees, no more single malt for you)
Personally I think all passengers should have to pass a short course before being allowed on an aircraft, licensing them on O2 masks, life jackets, door operation and how to refrain from pressing a call bell. Tips on how to travel light, understand timezones and pass efficiently through metal detectors would just be an added bonus for all.
Passenger licensing, you know it makes sense.