Facebook is now testing a new ‘Green screen’ option within the Facebook Stories creative tools, which will enable users to overlay their video over a selected video or still image.

The new Green Screen option would be available within your Stories creation tools. Once selected, users will be able to add a photo or video from their Camera Roll, which will then be added as the background. Users will then be able to film themselves or post a still image that would be overlaid over that background visual.