Wall Street Journal: Twitter is officially rolling out ads that will play automatically in a user’s timeline, taking on the dominant forces in online video advertising, Google and Facebook. When users scroll through their Twitter feeds and see a video, it will begin to automatically play while muted. Clicking on the video will play it in its entirety in the full-screen viewer with sound. Think Facebook-style video, as opposed to the model that requires a click to start playing. The auto-play function, which the company has been testing for several months, will apply to all video content uploaded directly to Twitter, including GIFs and six-second Vines.