I posted this question in this video's original thread in spectator's balcony, but received no response so far.
YouTube - The Belly of the Beast
Anyway, shouldn't the inboard slats stow when the thrust reversers are deployed during landing ? Or is this function found only on the 744s ? Was of the impression that it affected all B747s as it had something to do with hi-frequency vibration damaging the slats (krueger flaps) during thrust reverser deploying.