Lonewulf:
Believe it or not, the producers of content are usually the ones that submit content to tube videos. This is called "advertising" as the websites are not always as widely known or recognized.
Believe it or not, I don't believe this.
The content creators that I referred to (including Realspankings, Shadowlane, Punished Brats) are some of the best known video producers out there. Whilst they might post short clips, trailers or snippets to SpankingTube, they aren't releasing whole videos in exchange for "advertising" on porn sites. Then there are the sites that post entire library's worth of videos stolen from various producers, which is certainly not advertising undertaken by the producers.
Content creators like Michael Masterson and Dallas are extremely vigilant in calling out stolen pictures on Fetlife, so I doubt they're secretly releasing their own videos to the tube sites for advertising. This topic is covered from time to time on the "Never too old for Agoodspankin" podcast, and each time the comment from the creator is that the stolen content is making their job increasingly difficult.