Interesting, never really thought about that. Another benefit of having the wolf's back is the health of the remaining herds is better. They cull the weaker, sick.
You won't hear any of the elk hunters pointing that out. They like to take the best of the gene pool for trophies. I have no problem with hunting. It just seams kind of stupid to kill your best breeders. Watched a hunt in Europe. Red stag I believe. The guide (you have to have one) picked your animal. If you were really lucky, you got to shoot a old bull. Past his prime. Otherwise it was whatever he thought the herd needed the least.
In the mid-1980s Alston Chase's Book "Playing God in Yellowstone..." created a stir. In it he talks at length at some of the National Parks policies and decisions that effected the natural ecosystems of places like Yellowstone. While he had some obvious biases he discusses in detail the changes that occurred within the Parks' ecosystem with the elimination of the wolves. If one is interested in such things the book is a good (though long) read.
What is really surprising and interesting is how quickly the ecosystem has responded to the re-introduction of wolves. The wolves have been back in the Park for less than 20 years but as the video points out many of the impacts from the elimination of wolves some 70 years earlier are in the process of being reversed.
I visited Yellowstone in 2001 and again this year in 2014. I did not see evidence of the dramatic claims made in the video. I did see less elk and buffalo. Also they were restricted to/or missing from certain areas of the park.
The biggest issue with the Yellowstone rivers is the lack of cutthroat thst move out of the lake to spawn- bucket biologists put mackinaw in the lake and the cutties are getting wiped out.
Read an article recently making the claim that the cutthroat, not the wolves, are the true keystone species for Yellowstone
The loss of the massive trout spawning runs has severely impacted the bears, the birds etc