Why is HTML5 video timestamp in hours:min:sec for a 50 second video?

Question

I have a basic HTML5 video player with a video from my server. The problem is the timestamp. It's displaying as

470:58:14 / 470:58:21

I've never seen this before and I can't find documentation as to why it might happen.

HTML

<video controls controlsList="nodownload" poster="img/wallpaper.jpg" preload="none">
  <source src="videos/title.webm" type="video/webm" />
  <source src="video/title.ogg" type="video/ogg" />
  <source src="video/title.mp4" type="video/mp4" />
  <p>Your browser does not support HTML5 video. Please use Chrome, Firefox, Edge or Safari to view this content.</p>
</video>

Timestamp