Evacuation video.
It has been said before, but under stress humans revert to a known pattern.
These guys were getting off an aircraft - which means you open the locker, get your bag and head for the exit, which is what they were doing.
The lack of smoke/fire (initially) meant that there was no real impetus to get off.
Even the landing itself may not have seemed unusual to infrequent flyers.
I flew with the rear cabin crew member on the BA Beijing 777 which pancaked at LHR.
Even she, as a seasoned cabin crew member was flabbergasted to see the aircraft on its belly having evaded, having experienced more violent "normal" landings before.
Probably compounded by mostly none English speaking Indian nationals, which meant that any cabin crew exhortations were not understood.
Don't blame people for being human.