The file preview supports images, .mp3 audio files and .mp4 video files. Confluence uses HTML5 to play attached audio and video files. With the multimedia macro, you can embed a wider range of multimedia content on a page, such as animations. In the macro dialog, type “Multimedia” and click on the macro.
Pick a file from the list of all attached multimedia files and click “Insert.”
When you save the page, you’ll see the content in the file preview where you can, for example, play the video.
Watch our Video #24 of the video tutorial series “Learn Atlassian Confluence” and read this info in Atlassian’s documentation about this subject.