Facebook videos are extremely popular, extremely. By the end of 2016 Facebook users were watching 100 million hours of videos every single day! With this popularity it only made sense for Facebook to monetize their videos.
What Facebook decided to do was integrate ads 20 seconds into their videos, and then share the revenues with their publishers. Currently the breakdown is set at 55% of the revenue going to publishers!
An important note is that many of the Facebook videos are rather short, and nobody wants to watch a commercial during a 30 second video. To help fix this Facebook has setup ads to only appear on videos longer than 90 seconds – as such publishers are encouraged to produce longer content to increase their revenue.
Not everyone will experience the ads yet – however they are on the way. Expect them.