I recently flew with SA low-cost 'Kulula' & the demo was done in a very humourous way - and everybody paid attention as result.
I agree that it is very annoying to see people buried in their papers whilst the demo is on. I would love to hear an F/A saying '... and those of you who can't be bothered watching me now, well, I might not be bothered risking my neck to get your panicking a55 out'. I seem to recall that, for a while at least, Qantas' demo video had a line which ran something like 'Look at the crew member in front of you now. It is this person who you will have to take instructions from in the event of an emergency'. It needs to be personalised - people need to know it CAN happen to them. I recall flying the day of SQ6 - CNN had been on in the terminal. Very attentive bunch that day.