To answer PopsicleStand's concerns, you are absolutely right! That was by far the sketchiest rope swing setup I have ever seen. I'm truly surprised someone didn't get seriously hurt or die. In the climbing world, a very, very common saying is "metal on metal = death." You do NOT clip carabiners to other carabiners. The overall rigging of the anchor, besides the carabiner on carabiner element, was terrible. It was exerting forces on the biners in a crossloading manner. When a carabiner is crossloaded, it is drastically weaker, and more prone to failure. These were also aluminum carabiners, which are less than ideal for this type of application. Steel carabiners should be used, as steel bends, while aluminum breaks. Lastly, all of the carabiners I could see being used (including on the harness I believe) were wiregate, non-locking carabiners. In an anchor, locking carabiners are a must. If those guys make a habit of doing this, and do not receive better instruction, someone WILL get seriously hurt. Take the time to learn the art of rigging, how forces are applied, and how to make a properly redundant and equalized anchor.