The DITA Open Toolkit that comes bundled with Oxygen XML Author Eclipse plugin includes a pre-installed plugin that allows you to embed well-formed HTML content directly in a DITA topic.
For example, suppose you wanted to embed a YouTube video directly in a DITA topic.
....
<foreign outputclass="html-embed"><![CDATA[
<iframe width="420" height="315"
src="https://www.youtube.com/embed/qepRkQxhTX"
frameborder="0" allowfullscreen="true">
</iframe>
]]></foreign>
...............
<iframe width="420" height="315" src="https://www.youtube.com/embed/qepRkQxhTX"
frameborder="0" allowfullscreen="true">
</iframe>
............The plugin is also available on the oxygenxml GitHub projects page.