To try and summarize this quickly, though, what appears to be happening is that when a video is added to an Article in Zendesk via the Add Video icon…
… then Zendesk uses an iframe for this purpose. And, when viewing the source code (HTML), it is valid (notice the closing </iframe> tag)…
But, when viewing the source code for a translation file for the actual article in a browser, the iframe gets changed to a self-closing tag, which isn’t valid HTML, and this is the cause of the issue where nothing displays after the video.
There is test after the video, but nothing gets displayed after the video because the iframe is no longer valid HTML.
As this is going to require more investigation, let's look at this on the private ticket.
Best regards,