That is an interestingand beautiful video, it truly is. However, some of the things they are saying do not work with the pictures they have used. What they are calling "deer" are mainly pictures of elk. Elk are much larger than deer, and are more of a grazing animal; wheras deer are more of a browsing animal, and eat more of twigs and small branches and leaves, and not as much of the grass.
Some of the pictures seem to even show moose, and they just label all of these very different creatures as deer.
Truely, the wolves would probably happily devour both fawns, and elk or moose calves; so they probably did chase all of them back into safer areas.
The wolves have also now spread into areas of both Idaho and Montana, and are also killing off lambs and spring calves from the herds being raised by ranchers in these areas, and probably this is also happening in other areas close to Yellowstone.
Since wolves are protected, there is not much that the ranchers can do to keep them from killing the cattle and sheep; and this has become a real problem for farmers. There is no real way to keep the wolves in Yellowstone.
Not only the wolves, but the grizzly bear, have been moving closer to inhabited areas in nearby states. People in north idaho, where I used to live, have had several occasions of grizzly attacks, right in their own yards, and also had their livestock killed.
One morning, I found huge pawprints outside our place, which were way too large for coyotes; and I think it must have been a wolf, looking for something to kill and eat. I always had to make sure that I was close to my dogs when we were outside.