Are there any extensions that are causing issues?

Very doubtful, as I’ve tried this on vanilla installations of various browsers.

Anything in the browser console?

Now that I check, I do see some DOM exception errors in the console, which seems to happen when the UI freezes.

The errors come up after I’m able to interact with the UI (video remains playing throughout):

Uncaught (in promise) DOMException: The fetching process for the media resource was aborted by the user agent at the user’s request.

This might be the first place I should look to find a solution.