"Without a specific method for comparing the actual acceleration to that required, flight crew must rely on comparing the ‘feel’ of the takeoff with their previous experiences. Because the reduced thrust takeoff optimises the takeoff for the local runway conditions and the aircraft’s weight, the acceleration for the aircraft can vary with each takeoff. Due to the variations in runway conditions and weights experienced by flight crews in civil transport operations, that variation can be quite large, and not necessarily directly related to the aircraft’s weight. Therefore, flight crews cannot reliably detect degraded performance until there is something more obvious, such as approaching the end of the runway without lifting off."
While hesitant to cast a stone from within my glasshouse my immediate reaction watching the animation was that if that passed for 'normal' acceleration then that variant of Airbus A340 is more underpowered than I have heard it to be. The acceleration was pitiful.