I have seen this video a few times in the past. Interesting theory, but a real stretch to attribute all of that to wolves. Also an outright lie in there as well. They state that humans "could not" control the deer population in Yellowstone, to my knowledge since it was made a National Park(like all other National Parks) there has not been hunting allowed by the general public of any kind, especially anytime in semi-recent history, so of course humans could not control the cervid populations. I believe they may have had Government sharpshooters in there at times, but we all know how successful they are controlling the hog populations in problem areas, so it stands to reason that they would have issues controlling the populations of other game as well(like the deer herd in the WI CWD Zone). Given the opportunity, hunters could have controlled the "deer" populations and brought about many of these changes by reducing cervid numbers just like they do all around outside the Park. As I said, a huge stretch and some misinformation.