It's a promotional trailer for a video series on weight loss that emphasizes a whole food plant based diet. The video is mostly stock footage of food production, medical stuff, and people exercising with audio from various speakers (Alan Goldhamer, Brenda Davis, Scott Stoll, Hans Diehl, Neal Barnard, Michael Greger, Joel Fuhrman, Dean Ornish, Stephan Esser, Angie Sadeghi, Steve Lavenda, Chef AJ).
The speakers talk about things like "hyper-palatable foods" which stimulate dopamine production and how companies produce unhealthy food to maximize that effect. They draw a link between those kinds of foods and depression via dopamine sensitivity. Medical school teaches doctors the things they will be reimbursed for rather than what keeps people healthy, and there's only about 4 hours of actual nutrition information. They say DNA is not our destiny, and that lifestyle changes affect our epigenetics.
I agree with you that veganism shouldn't be promoted as a weight loss diet. I think a lot of people fail at transitioning because they unwittingly aren't getting enough calories...intentionally trying to minimize calories on top of that is likely to fail like so many other diets. But I think this video is promoting long-term lifestyle change, rather than a get skinny fast scheme. More of a way to use peoples' desire to lose weight as a lure to get people to consider a WFPB lifestyle.
The video series is free ("for a limited time only") but it looks like you have to register to watch it, and the website looks like it's using a lot of marketing techniques. Maybe the host Chef AJ is trying to sell cookbooks off it or something. The message seems totally on-point though.