You are describing most youtubers and seem to be surprised that people spend many hours editing tons of videos because they want to make money, and not out of the goodness of their hearts?
You are conflating getting paid by someone directly, versus being an affiliate. Some people make this distinction and some do not. A lot of poker pros would also say that they don't work for any poker sites, even as their materials are littered with affiliate codes and promos. It is a fair distinction - annoying but fair.
Most people do not disclose how much they get paid by their employers. Brad Owens and Andrew Neemie do not tell us how much casinos pay them for each person they bring to their meetup games. It is ok to be curious and I am curious too. Poker app affiliates do not tell us how much they skim. I personally do think it falls under "shadiness" - but I do not think it goes to the level of "scam". Walmart does not tell you their wholesale price and how much they make on you when you buy shampoo at Walmart, either. It's just business.
Just like everyone else, they need to get permission to film and depending on how the casino feels about it, they might get it or they might not. This is why some of the casinos with lenient video rules keep showing up, this is why some of these players ingratiated themselves with a few specific casinos so they keep taking there, and why some casinos do not appear in any videos at all. IIRC, Cosmo is very lenient and pretty much anyone including you can go record your action...
It should be obvious that they show the glory of winning. No one wants to watch losers. This goes for most gambling shows. Gambling is a business of deception and that goes for slots as much as it goes for poker: most people will lose big. I can only imagine how many kids derailed their lives hoping to become poker pros after everyone was beating into their brains how awesome it is to be a poker pro and how awesome poker pro lifestyle is.
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Most of what you describe is business 101 and only slightly shady at best.
But I heard quite a few rumors about these people. For example, I heard that the casinos give them promo slot dollars that have no actual value to play so that it looks like they are gambling huge and winning huge, when in reality they are not.