Jewett’s right heel on his back kick hits Amos’ left shin below the knee.
So Jewett can’t cycle his right foot to land properly and he goes down.
Amos stumbles at the initial contact and trips over a fallen Jewett.
It’s an unfortunate accident where really no one should be advanced.
If that happens in the final, they don’t get a medal for falling and won’t rerun the race.
I have no idea how Amos gets in over Jewett.