Never been in that situation but agree with what they say and the same is true for a lot situations with a car. One biggie you need to keep in mind is getting the window down for an escape if/when opening the door is a problem, or an impossibility. Most cars have power windows and if the electrical system is inoperative you can't roll it down. So you want to do that quickly, as while you can because you might not be able to if you wait. I'm not sure if getting the seat belt released before getting the window down is the best sequence, you got to get both of 'em down and there may be a time-fuse element on the electrical system.
That little window breaking emergency tool was interesting as we are having a bad rash of car break-ins in my area where they break a window. I never thought of them using something like that but that would be an ideal tool for that. I recall seeing some kind of tool like that years ago that also had a razor blade attached like a letter opener to cut away a seat belt that wouldn't release in an accident. Problem is you have to be able to get your hands on that tool very easily and quickly... so how do you do that? If it is laying around it is going to get tossed on impact.