Board Thread:General Discussion/@comment-45179479-20200327101913/@comment-9605025-20200327153426

You cannot link to YouTube using the format. Using to link to something that isn't on your wiki requires a predefined interwiki prefix and YouTube doesn't have one. If you want to link to YouTube, you need to use the [] format. If what you are trying to do it upload a video from YouTube, then you can do so by going to Special:NewFiles, clicking the "Add a Video" button, and then provide the URL of the video.