By detecting the rapid deceleration of the hidden car ahead of the Tesla, AP did for all practical purposes "predict" the accident. After all, there was indeed an accident a fraction of a second after the AP made the alert sound. If that isn't a "prediction" I don't know what is. In effect, when AP detected the hidden car braking it "predicted" that an accident could occur and it applied the brakes.
Consider this: Tesla owner is driving on the highway, everything seems normal. AP is monitoring the car immediately ahead AND the next car beyond that car. Let's call them Car #1 and Car #2. #2 suddenly decelerates, #1 does not (no brake lights visible on #1), AP detects #2 decelerating and alerts and brakes before Tesla driver notices #2 decelerating and before he can apply his brakes. Then #1 brakes but too late and hits #2 at which point it hits the center guardrail and rolls. Tesla has safely brakes to a stop.
My viewing of the video suggests that if the Tesla driver had not been running AP he would have brakes too late and hit #1. I can't know that for sure, but based on the video and the Tesla drivers statement that AP braked before he did, it appears that AP prevented the Tesla from being involved in that accident.