Release
YouTube will contact the poster when the ad reaches a certain amount of views; it used to be 1 million, but now is much less. They ask poster if ads may be attached, from various companies, from which the poster will receive 'royalties'. These payments are not chickenfeed if the post attracts 100s of thousands/millions of viewers. They aren't even chickenfeed to begin with. And checks are sent every month to posters.
This is the reason you see so many fucking 'kitty' & 'baby' posts on YouTube. It's said they are the top 2 attractions there. Even higher than the hulahoopsters and (next to) porn.