Missing error handling on broken video assets/metadata

[mblomdahl]

When I open a video like this one, https://OwnTube-tv.github.io/web-client/video?id=a56faeff-d41e-46c6-93fc-9e01eab8383c&backend=media.privacyinternational.org (https://media.privacyinternational.org/w/mqSpbxWucBxnUYA4JvawAq), I get a black screen instead of playback. If I open the web inspector, I see that the browser is busy downloading a huge mp4 video file (and failing) in the background, see 345.5 MB (and counting) on the data transfer meter:

Instead, I would like to see a error dialog about "Video playback broken, return to previous page, yes?" and not have my data traffic eaten up in the background.