Videos
Videos can be referenced in a DITA topic by using the 
  <object>
      element:<object data="path/to/video.mp4" outputclass="video"/>How to Reference a Video Using a Key
Videos can also be referenced in DITA topics by using a key.
The key must be defined in the DITA map like
      this:
    <keydef keys="video" href="path/to/video.mp4" format="mp4"/>The key is referenced in the topic with the 
    @datakeyref attribute within the
        <object>
      element:<object datakeyref="video" outputclass="video" width="480" height="270"/>How to Change Video Size
It is possible to set the size for your videos directly from a custom CSS
      stylesheet:
  .video {
  width: 480px;
  height: 270px;
}How to Change the Videos Cover
By default, a placeholder is displayed in place of the video. When clicked, this placeholder launches the video. A popup is presented in Acrobat Reader to enable the Multimedia content (the document must be trusted for the video to launch).
It is possible to change this placeholder with a custom one by using the 
  -oxy-video-cover
      property:.video {
  -oxy-video-cover: url("files/cover.png");
}How to Center Videos
It is possible to center the videos by centering their containers like
      this:
    .video-container {
  text-align: center;
}