I honestly don't think that an engine fire on start is going to require an exit so fast that fumbling a door catch is going to matter.
Pax evac briefing is more to do with catastrophic "if i'm not there to help you" scenarios, surely?
If an aeroplane is on fire people don't need to be told to move away from it quickly, that happens naturally. You're far more likely to need to stop them from leaping out into a running prop while you're blowing through an exhaust fire and some twerp outside is screaming "Fire, fire". In that scenario, and no amount of pre-briefing will have any affect on their attempt to run - a blocking arm across the exit and a cry of "STOP!" will be required. If they do need to leave, "THAT WAY! GO!" is the formula.
But surely best time to demo belts, doors and brief is in the quiet before all the interesting and distracting things start to happen? That is, when you shouldn't be distracted either.
Last edited by Agaricus bisporus; 12th Jan 2011 at 15:35.