Found a nice little code snippet for making responsive videos on Bootstrap 5 based websites, such as Hubzilla.
<div class="ratio ratio-16x9">
<iframe src="https://example.social/videos/embed/1234" title="PeerTube Video" allowfullscreen></iframe>
</div>
https://getbootstrap.com/docs/5.0/helpers/ratio/You can see it in action here:
https://federatedhub.org/page/video/the-fediverse-is-quiet