I have noticed that there is always a few passengers who pay no attention to the safety demonstration and can be disruptive.
Safety announcements and demonstrations are very important. I want to make sure I have a very good idea of what I need to do in case of emergency. And so what if you have seen them thousands of times? Have a little respect and even if you are not interested pay attention and make it look like you are interested....
Safety announcements
are important - I'm not going to doubt that. Of course, after countless times of hearing it (e.g. during an MR), it can get very repetitive. That's not to say it isn't important or a pointless exercise.
For me it's like a safety induction when you go to a mine site. It's a boring five minutes of video (and at one site I've been to before we even had to take a test and pass it before we could enter), but it's a quintessential safety step.
I find it impossible to do much else whilst the safety demo is on (it's hard enough to talk to your neighbour, listen to your iPod or concentrate on what you're reading), so I normally tune in anyway.
To be honest, the video could say all of the suggestions that you've made above but the reality is, about 1 in 400 people on board the plane are actually paying attention anyway. Also 1 in 1000 actually do as they are told. I mean how hard is it to stay seated till the SEATBELT SIGN IS TURNED OFF!!!!
The safety demo could say "If you ever need to use the emergency brace position, put your head between your legs and kiss your a$$ goodbye" and nobody would notice.
This streams from a new age thing where there are so many warnings around people they simply ignore them. Software engineers would know this first hand.
How many times have you got a software warning but simply said, "yeah yeah yeah, just do the d*** task already"? It doesn't seem to matter if the message was "Do you wish to delete....", "Are you sure you want to accept this unsigned certificate?", "Continuing may result in data loss, are you sure?", experts have found that people are almost immune to warnings.
On the other hand, without such warnings, people could claim, "Well, I didn't know it could do that, so it's not my fault." (A nice example is a recent article about some idiot who purchased a $1000 iPhone app "by mistake".) Of course, we live in a society now where any misfortune seems not to be the fault of the person themselves, no matter how stupid they may seem compared to an "average, rational human being".....