From the video comments by the woman holding the rifle while it exploded:
The 7th round jammed, which is nothing unusual for this gun. It happens all the time. That is why I didn’t really hesitate to shoot the final round. I was very lucky with the outcome. I have lots of splinters and bruising, but nothing broken. My left hand took the brunt of the blow to my wrist and palm of my hand. Still pretty painful, but I will be fine.