A little knowledge can be a dangerous thing.
If I understand correctly, pilots perform checklists because even though they may know by heart the procedures, the checklist serves to check and remind and establish a pattern for subsequent procedures. The same is true for the verbal briefing on taxi out for an abort or divert: It re-enforces agreed procedure and understanding.
ukhomerj - wouldn't it be easier to just watch the damn thing? What's 60 seconds out of your life? When I position with pilots on commercial flights, they watch the briefing, even on their own aircraft: It's a courtesy thing - sets an example to others around. Also, for the reasons above it can be useful.
Don't get me wrong, you can do what you want during the demo (so long as your newspaper or conversation don't obstruct others), and who knows maybe you are as knowledgeable about SEP procedures on that type and carrier as you believe. It just seems to me that for reasons of common sense, courtesy and professionalism you might as well watch rather than try and buck the system. It just seems to me to be such a terribly small imposition to place on you, but hey, who knows? I rarely see it from the passenger side.