Truck loses trailer while going down the highway

Screen Shot 2017 01 28 At 10 00 46 AmIt may not be the most important thing to do when driving, but keeping the trailer attached to the truck must be one of the most important ones. While it takes a little while to develop, this video makes it clear that something, somehow went wrong and the truck and trailer parted company. Any ideas how this could happy? Ever happen to you?