Yeah, referring to youtubers and twitch streamers who get money to promote their games, only they are more often viewed as "neutral", and thus their supposed enthusiasm of the game gets viewed as the game is good, which creates sales. Meanwhile they are getting paid to do so, while also being under contract. These contracts range from be sure to talk about these key points to not allowing any negative comments. Shadows of Mordor being the latest example of a draconian contract that got whistleblowed by TotalBiscuit, but not before it was featured on lots of channels on both youtube and Twitch.
ManVSgame for instance did a 8 hour stream of it, saying quickly that it was a paid promotion, but after the contract was leaked, it was extremely obvious that he followed the contract down the dotted line, effectively making it a 8 hour commercial because every time he hit a negative bump or bug, he was always extremely positive.
On youtube, Yogscast has gotten a bit shady with their promotions of games, and lack of/hidden disclosures that they are doing paid promotions. Since their demography is of a fairly young age range, their audience is particularly vulnerable to these kinds of promotions. TB, while being their "friend" so to speak, has been quite vocal in his criticism of their business practices of late.
Some people disclose paid promotions though, so it is safe to say that if you see one youtuber say "this is a paid promotion", then you see the same game pop up on other youtubers channels in roughly the same timeline, they are most likely all paid promotions.
It is all a very gray area at the moment, from the ethics behind it, to what might even be considered illegal in terms of age ratings. If you know a demography of a channel is 12-16 and you pay for a 18+ game to be featured there, because you know that will push sales (as most parents just seem to buy whatever their kids want these days), it is shady at best. Not sure a 18+ game would be allowed to feature as a TV commercial on a kids TV show.
At the moment youtube and the various streaming services is a delicious buffet of cheap and effective advertising that is hardly regulated at all. Where the especially effective part being that it is displayed by what is regarded as regular people, not promotional salesmen with an agenda, though that is what many of them have turned into while maintaining what is now only an illusion of being unbiased.
