Great video, possibly giving too much credit to the wolves.
In one article it is refuted– a study showed that we had gone too long before removing some of the elk population. “After humans exterminated wolves nearly a century ago, elk grew so abundant that they all but eliminated willow shrubs. Without willows to eat, beavers declined. Without beaver dams, fast-flowing streams cut deeper into the terrain. The water table dropped below the reach of willow roots. Now it’s too late for even high levels of wolf predation to restore the willows.” Is the Wolf a Real American Hero?, Arthur Middleton, New York Times, March 9, 2014