In the month of Spetember 2013, Facebook launched a new feature of "Auto Play videos" for mobile devices. Means when a user connects to Facebook on his mobile, the News Feed will display the videos automatically for them.
As the testing of this feature has been successful, Facebook is making it available for all mobile users now.
The feature when became successful, it has been seen in some Facebook users on their mobiles which is now available for all iOS and Android users.
For desktop users, the feature is still in the test mode and will soon be seen by them too. It is not schedules to when it will be available for the desktop users.
On your mobile devices when you scroll the News Feed, the videos which are uploaded by others are automatically played and if the user wishes not to watch then by scrolling the feed will change the screen to the other videos if uploaded.
Move the videos as you move the photos on screen. Watch the videos when auto played and if you find it interesting then like or comment on it. If not just make a slight disruption and scroll the screen down. The video will not play.
So wait for the latest feature called "Auto Play videos" which is newly tested and successfully implemented. This feature will be internationally available to all mobile users.