Wow, I never knew that a powered-down iPod was less likely to become a projectile than one that is turned on. You've really educated me on the physics in the imaginary world that you inhabit.
And as to ignoring the safety breifing, who the F cares about the safety briefing? It's the same thing every time and it's all common sense information. Really, the nearest exit might be behind me? My seat floats? Wow, I'd be dead in a crash if I didn't hear those little nuggets of wisdom for the 7 millionth time.
If the alertness of the passengers was as important as you claim, nobody would be allowed to sleep, eat or go to the bathroom on planes; nobody would be allowed to read books, newspapers, magazines, etc.
The problem with repeating this "you don't know how many times" is that everyone already knows that it isn't true. Repeating lies over and over again just convinces people that everything you say is a lie (c.f. The Boy Who Cried Wolf)