The other thing to notice in the Twitter video is the path of Jewett's right leg back kick. Quite high and clear of trouble. It disappears behind Amos' right knee (Amos' knee is closer to the camera). Watch where Amos' left foot plant is within lane 1 (just about dead center). In the stride where Jewett contacts Amos' left knee, Rotich is beginning to move up on Amos and Amos drifts slightly right. Amos' next left foot plant is on the outside edge of lane 1, so he has moved to the right a few inches which puts his left knee directly into the path of Jewett's right foot. You can see Jewett's right foot go back, and this time his foot is closer to the camera than Amos' knee (thus on the inside). You see Jewett's right foot twist to the inside, and when his foot moves forward you can see his foot hook his left calf. Then the fall occurs.