Why auto play videos?

For my own curiosity, this is more of a metrics question. Why does every site these days force video content on users? Every article seems to lead with a video that auto plays AND follows the user down the page. As far as UX, I find these types of things terribly intrusive and disruptive. However, there must be some reason companies are doing this.

Is there some kind of metric they are trying to hit? Thoughts?