> Forbes, TheHill, LinkedIn, and various other sites now just auto-play videos following right in facebook's footsteps.
Yes. And I believe these companies are trying out the Facebook recipe for Advertizing -- which leads to monetization and profits -- success.
It's been widely reported (you can search HN archivesa and you'll see) that Facebook counts as little as 3 seconds of any video play time as a "View". And it takes the average user about that much time to scroll down or up, at which point the currently playing ad stops playing, and the next one in the viewport is now playing on autoplay. So a single user could potentially be scrolling up and down his/her page / feed, and contribute 10 to 20 Video views.
Scale that to it's millions of users, and Facebook now presents the video views as "Reach" and can charge advertisers a lot more.
From an end user perspective, it's annoying, but from the publisher point of view, it's in the interest of all these sites to auto-play their videos, and count a few seconds as "Views" and tout their reach eventually leading to increased ad sales...