I think people are missing the point of the video, which isn't necessarily advocating for veganism or vegetarianism. They argue for a reduction in meat consumption, and especially a reduction in ruminant meat (cows, sheep, etc.) consumption.
For those that didn't watch, if everyone on the planet reduced red meat intake to once a month and cut other meat consumption to one meal a day, global greenhouse gas emissions could be cut by 14%. That is roughly equivalent to the emissions generated by all forms of transportation combined.
Edit: Reducing meat consumption is also the easiest way to reduce your individual impact on global warming and environmental degradation.
Depending on where you live and how local electricity is generated, an electric car might actually generate more emissions than a gas-powered car. Plus the production of electric vehicles generate a considerable amount of greenhouse gases, not to mention the materials that need to be mined and refined to produce them.
This seems to wildly vary from person to person. But the greatest impact by far seems to be having fewer children
That is not to say that people should be eating less meat, which they probably should.