Hmmm... hard to tell much in the video, but the break appears to have a rounded aspect, as opposed to a jagged edge look. It broke like pottery, not like glass. That says bad metal to me.
The puzzling thing is where it broke. The separation is in a place that should have webbing (and therefore load) on one side, but not the other. To break there, the webbing would have had to be on the hook. The webbing must have shifted onto the hook, with very little of it where it is supposed to be.
But, it's hard to tell from the video.