From the video description
The zip line is was home made, and obviously not very safe. The handle broke, causing the rider to backflip off the seat. She could have easily broken her neck, but fortunately she survived.
From the rider:
“As a result of the fall, I fractured my pelvis and spent 6 weeks basically bedridden, and then another 6 weeks in pain. A year later I went on a hike that severely aggravated my pelvis, but since then I have had no long term effects.”