I think what he's missing is that the junk yard is generally paying to have the "used fuels" hauled off and disposed of properly, not selling it. One of the commenters under his video said the going rate in California used to be roughly $350/55-gal bbl, so if the fuel delivery company charges the prevailing rates, they're starting out roughly $6/gal ahead. If they can sell it for $4/gal to the retailer, that's nearly $10 in profit (after you take out the actual cost of transporting it, which is most likely negligible) where they might be lucky to make a dollar or two per gallon on "new" gasoline.
If you have 5,000 gallons of it and you're rolling out, say, 20 tanker trucks at ~11,000 gallons each to service customers, you're only putting 250 gallons in each truck. That's probably not enough bad gas for anyone to notice (less than 0.25% of the load), especially after it's been sloshed around with the good gas in the truck and in the station's tanks (one reference I found said that gas station tanks usually hold 11,000-24,000 gallons). It's going to return a $50,000 profit and be dang near undetectable. Hell, it allegedly went twelve years (2009-2021) without being detected.
That's a pretty slick racket.
