It wouldn't surprise me if that vid of the yotes taking down an Elk was from the Yellowstone area. When I lived out there they wolves were still getting reestablished. While the Wolves were gone they biologists talked about how the Yotes had basically taken there place and hunted in pack form vs smaller family groups and that there size was significantly larger than the average Western Coyote.

We have a sheep shearer who basically traps coyotes in the off season since he is so bored. Takes out 2-3 times as many coyotes in an area than hunters do. Clears out areas real fast. Hunting alone would never do it alone. They got rid of them way back when with poison, traps and hunters.