I had a really hard time following this presentation. This is what I think he said:
1. Emergency brakes were dragging on the main cable.
2. Because of this, the pull cable was stressed beyond it's capabilities and sustained damage.
3. A technician fixed the root problem by disabling the emergency brakes.
4. The damaged pull cable eventually broke, and with no emergency brakes, gravity finished the job.
I couldn't discern whether the video was claiming this as a possible hypothesis, or a factual report.