When posting a URL like https://www.youtube.com/watch?v=DHradnt7rQk XenForo turns this into [MEDIA=youtube]DHradnt7rQk[/MEDIA]
This works fine to embed the content - as long as provider youtube is available and enabled in XenForo.
If it is disabled or no longer available (maybe because it was provided by an Add-on that was removed) nothing would be displayed - which is not helpful at all for the average user.
I therefore suggest to modify the BB code so the original URL can be retained, maybe smth. like