Dive summary: 

• Facebook is beginning to test the auto-play video feature in users' news feeds; the first wave will not include any advertiser videos, only videos from individuals, musicians and bands. 
• The test is exclusive to mobile users and will roll out over the next few weeks. 
• Videos will appear and start playing, but silently; users will have to turn on the sound if they wish to hear it. 

From the article: 

“'At first, this feature will be limited to videos posted by individuals, musicians, and bands,' Facebook’s Kelly Myers writes. 'We’re doing this to make sure we create the best possible experience. Over time, we’ll continue to explore how to bring this to marketers in the future.'”