Count the number of strides. He does 41 or so in a 100m race and he did 20 or less (depending on when you want to say he shut it down) in that video, so we’re talking 40m or so, could even be less (41 strides in a 100m, but the ones after 50m are significantly longer with ones at the beginning significantly shorter, so more plenty more steps for the first 50m).