Memes

That video cites a number of heavily misleading stats. Here's one video looking at the problems with that video. If we look at that very same study for that 80% claim it also notes that it still takes more human edible feed

1 kg of meat requires 2.8 kg of human-edible feed for ruminants and 3.2 for monogastrics

https://www.sciencedirect.com/science/article/abs/pii/S2211912416300013

Using all available land still very much has a cost when it comes to things like deforestation. Clearing land for pastures is the leading cause of deforestation in the Amazon

Extensive cattle ranching is the number one culprit of deforestation in virtually every Amazon country, and it accounts for 80% of current deforestation

https://wwf.panda.org/discover/knowledge_hub/where_we_work/amazon/amazon_threats/unsustainable_cattle_ranching/

Additionally, it still takes more arable land as well

The research suggests that it’s possible to feed everyone in the world a nutritious diet on existing croplands, but only if we saw a widespread shift towards plant-based diets.

[...]

If everyone shifted to a plant-based diet we would reduce global land use for agriculture by 75%. This large reduction of agricultural land use would be possible thanks to a reduction in land used for grazing and a smaller need for land to grow crops.

https://ourworldindata.org/land-use-diets

Water usage from growing animal feed is enormous in the places where it matters quite significantly such as the American West where it's the main driver of water usage. Over 50% of the colorado river's water usage goes just to animal feed

Correspondingly, our hydrologic modelling reveals that cattle-feed irrigation is the leading driver of flow depletion in one-third of all western US sub-watersheds; cattle- feed irrigation accounts for an average of 75% of all consumptive use in these 369 sub-watersheds. During drought years (that is, the driest 10% of years), more than one-quarter of all rivers in the western US are depleted by more than 75% during summer months (Fig. 2 and Supplementary Fig. 2) and cattle-feed irrigation is the largest water use in more than half of these heavily depleted rivers

https://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1064&context=wffdocs