DITA: Video

To embed video, you must use object tags.

Here's a sample embed: 
   <object width="640" height="360" data="//www.youtube.com/embed/vwh93zo7_oU?rel=0">
    <param name="src" value="//www.youtube.com/embed/vwh93zo7_oU?rel=0"/>
    <param name="movie" value="//www.youtube.com/embed/vwh93zo7_oU?rel=0"/>
    <param name="allowFullScreen" value="true"/>
    <param name="allowscriptaccess" value="always"/>
</object>

You can't use HTML5 video tags.