Well, most of us don't know how they do it, but we all know that these streamers are just promoting the casino (not unless, if they don't mention or show which casino they're playing), so most likely the casino have altered the flow of the streamer's game showing us more wins, which can be very different when we're the ones whos playing.
Therefore, your conclusion is correct. These streamers promoting casinos are just their to get paid, regardless if it's just pure deception.
If it is not live streaming, then, doubt the authenticity of the game results. Because the current tech can easily modify the videos that they can upload online. They can even skip some of the losing scenarios and show only the winning instances. In short, don't believe what you are seeing as they can alter what they want you to see.
Don't fall for it. If you want to gamble, do it responsibly. But know they ain't running charities. The games are stacked against you no matter what those streamers make you think.
Most of them are indeed paid. Very few streamers will promote certain site without any form of compensation. So yes, they will surely do their best to deceive their subscribers about the results of their game because they need to portray something catchy for the site they are being paid at. The tech these days are getting sophisticated, so quite easy to edit so fast and publish online.