That’s a good one. The staff group file is set so that it will display the description of the staff group, full width above the list of the group.
The only catch is WordPress by default won’t allow you to add HTML there, like a video.
There is a plugin called Allow HTML in Category Descriptions that I believe will let you add in HTML there. I haven’t tried the plugin, but it’s been around a good while.
What you’d want to do is copy the embed code for your video and paste it into the description of your staff group. To make it full width and responsive, before the embed code add this:
<div class="fit-video">
and after the video code add this:
</div>
See how that works for you. You could always edit the file, but this would make maintaining the site a good bit easier.
Bill