Facebook has implemented a 10-second rule, and we’re not talking about food that was dropped on the floor: In an effort to control social sharing of videos and other content from applications using its open graph, the content must be viewed by users for at least 10 seconds before those apps can share the activity to their timelines.
The social network said in a post on its developer blog:
Built-in watch and read actions can only be published after someone engages with the content for 10 or more seconds. If a video is shorter than 10 seconds, the viewer must watch the entire video.
Read more details on these social sharing requirements at allfacebook.