This is one of the reasons why I like the more novel safety briefing videos that you see from time to time, such as the Air New Zealand video based on LOTR. Something like this is much more likely to get (and hold) passenger attention than a crew member barking over the PA system.
I think that it'd be easier to keep attention if the briefing was optimised a bit into what is actually important -- is it really still necessary to explain to people how to close a seat belt in this day and age?
Just my €0.02...