They aren't useless. It can often be useful to know what the extremes are, as a middle-ground approach would lie somewhere in between. Like, if switching wholly away from animals would free up 3 billion hectares, would switching about halfway free up about 1.5 billion hectares?
Obviously it's not necessarily that simple but still, knowing the statistics at various extremes allows you to weigh your options, so you can compromise by combining various approaches at varying degrees and hopefully get a "good enough" outcome. The researchers here aren't necessarily saying "all you meat lovers need to just give up meat already, look at how much land we can free up!", rather they're saying "hey policymakers, if we reduce our reliance on animals by around a third, we can free up a billion hectares of valuable agricultural land."
To save people a click: that video is by a channel notorious for cooking videos filled with jokes. Avocado seeds don't have more avocado in them, it was a joke. The guy cut a seed open, carved out a cavity inside each half and filled that with avocado for the bit.
I tried it myself and looked the keys up. It gives you generic keys. They will work and let you install Windows, but they aren't "valid" keys so to speak. At the same time, they aren't "fake" either