It's iframe added into article called What we do, I guess you're using editor when editing content of this article, this editor may strip out the iframe tag and cause that issue.
You should go to Backend >> Global configuration >> set Default Editor to None and edit article again.
Here is the default content for the video:
<div class="videoWrapper">
<iframe width="560" height="315" src="https://www.youtube.com/embed/FqUW7bQuQuw" frameborder="0" allow="autoplay; encrypted-media" allowfullscreen></iframe>
</div>
You can simply replace the URL of your youtube video.
