Engine Failure on Short Final?
Having just seen the You Tube clip, the high AOA is clear, leading me to suspect the following possibility:
1) A/C begins approach fully configured with all engines operating (including full landing flaps, landing gear down, etc) for normal two-engine approach in accordance with BA SOP criteria.
2) Sometime after that, anywhere from the FAF to short final, one of the two engines experiences significant power loss (either mechnical, possibly injestion of flock of birds, fuel problem, etc)
3) "Engine Failure on Final" checklist attempted, including:
a) resetting and acheivement of higher airspeed target due to imminent use of lower flap setting (to lessen drag)
b) actual resetting of flaps to lower setting
c) resetting of ground proximity warning system due to use of alternate flap setting
d) possible securing of inop engine depending on time left and nature of problem.
The acheivement and maintainance of a higher approach speed with an inoperative engine at the same time one is attempting to maintain LOC and G/S while the flaps are being reconfigured (requiring an increase in pitch attitude) all while on final approach, IMHO, is quite a busy time. Any slight distraction can lead to exactly the nose high, high power setting on operative engine, flattened approach that we see on the You Tube clip. Perhaps following that with too high a sink rate once the road was cleared lead to the undershoot.
In other words, it's a handfull of airplane and procedures in the most critical of flying environments for which, IMO, there is barely adequate training for in the simulator. Engine failures in the traffic pattern miles outside the final approach are one thing, and practiced to a great extent. This kind of emergency, however, is quite a different breed.
In any case, my thoughts are with all involved.
RF