in post #124's video you can hear people shouting "we need to open the doors" almost the instant the aircraft stops moving. Both there and in post #149 you hear the CC immediately telling people to stay seated, but then you hear "no no no" and "we gotta get out" --
... highlighting the need for the pilots to get on the PA ASAP and say something! Even an alert to the Flight Attendants will placate the uneducated masses that they are not about to be left to their own devices.
Sure, this would be as close as you could get to a "surprise" event, but you have to be ready to spout out that PA under any conditions. The pax and your FAs are relying on it.