The post of ELAC, that BOAC refers to, mentions that on very short runways, manual braking is "envisaged". The question of BOAC seems to imply that this term means that autobraking is not to be used.
NOT SO! There is every reason to set the heaviest practical autobrake level (but Airbus states that MAX should not be used for landing), but then to try to manually win from the autobrakesystem by applying brakes quicker and harder. The "footshuffle" that BOAC mentions, probably leads to the practical result that autobrake applies brakes quicker, but pilot then counters with heavier brake pressure than autobrake would have given (don't managers call that a win-win situation?)
As we are witnessing here, manual braking will not give higher deceleration than even autobrake LO would have provided (we observe an average of 1.26m/s^2, with a peak close to 2.0 at the beginning of manual braking). Deceleration force delivered by the wheel brakes is limited by the friction coefficient (and the normal force on the wheels). Anti-skid keeps brake pressure near the optimum, regardless of autobrake or manual brake.
What can make a (possibly crucial) difference is that manual braking can be commenced with maximum pressure (limited by anti-skid) as soon as MLG touches down, before the nosewheel touches down. (This precedure is explicitly allowed, discouraged only for comfort reasons).
(Leaving aside possible foot shuffle; if necessary the PNF could prepare for manual braking while the PF is keeping the A/C straight with the rudder. Forgive me if this is so far outside SOPs as to be not considered.)
Autobrake MED has a 2 second delay (usually enough for a quick derotation), and LO has a 4 second delay (allowing for a slower, smoother derotation) after MLG touchdown; both apply pressure "progressively", which I read as slowly increasing.
I also understand "use of manual brake should be envisaged" as "watch autobrake closely and use manual braking as soon as possible when necessary". Except in the case of an autobrake failure I don't see the benefit of this course of action on slippery surfaces, since it will not give higher deceleration (assuming the friction coefficient tlimits deceleration to less than 3.0 m/s^2, and autobrake MED selected).
Bernd