And the fact you don’t hear the alarm on the video until the last “few feet to the surface” tells us what?
The alarm heard in the aircraft moments before the imapct with the sea has nothing whatsoever to do with the earlier alarm associated with the engine failure. The instrument group has more than one alarm to alert the flight crew with a warning. The alarm shortly before impact could have been a stall warning or other warning unrelated to the engine failure.
Basically, the stall warning horn coming on only just before shows the pilot to have reserved the final amount of lift available as kinetic energy for the area of “ground effect” (similarly for water). It means he pulled back on the yoke just before touching down, which is a good piloting technique for hitting the surface at the lowest possible speed.
HF