made some quick notes (so not a full and complete transcript) from an available short interview with one of the pax on board - who says he has not seen anything like this in his 30 years of flying - gives some background to some of the items discussed in this thread:
..... Middle of the night, 4 hrs out from Heathrow over the Atlantic to US,this tremendous turbulence happened, the word turbulence is not strong enough, there should be another word for it .... plane fell, 4x dramatic drops, 1st one(about a 1,000ft) after short shudder, then 3 other drops, most people sleeping with seatbelts on, woke everyone up immediately of course, babies crying, ... pilots said we had no warning, did not see this coming, ref’d Atlantic storm, pilots say do not expect more, but pax find that not reassuring, rest of flight was fine except “a few little shudders". Stewardess in galley area hit head bleeding along arm, guy standing next to her fell on floor, lot of people injured .....
This pax does not mention being told to sit down.