The root problem is not the cattle industry. The root problem is too many humans. Earth has finite resources, but outside of China it is considered immoral to try and reduce the human footprint.
Everyone switching to being vegan will not solve the root problem. Eventually the grazing lands will need to be converted to soy farms. The reduced biodiversity from everything being soy plants isn't any better. We humans are flooding the oceans with multiple forms of waste, and a worldwide population increase by billions is a big problem.
Mother Nature will continue trying to slow down the population growth with warnings. From new diseases to antibiotic resistant bacteria to increases in autism and other factors, either we need the warnings or suffer consequences on a massive scale.
Reduced human footprint reduces the cattle footprint and all agriculture footprint. The world should aim to have max 5 billion population, but even that is pushing resources so even fewer is probably better.
Instead we talk about increasing populations, and longer lifespans add to the overpopulation. Humans fail to stay within their environmental max footprint.
But instead we point fingers at the cattle industry and call them bad.
Movie claims they have determined the root cause of all these problems, but really the problem was, is, and will be the Human Industry that causes all of these imbalances in nature.