Linking to a Wikipedia article as a supplemental resource is not ideal but is acceptable. In many cases, a Wikipedia article offers coverage of a topic at a higher level of detail than an Encyclopedia Britannica article. And in a head-to-head comparison by the science journal Nature, Wikipedia was found to have, on average, only one more error per article than Britannica in science articles.
Before linking to a Wikipedia article, consider whether the subject of the article is likely to draw vandals who may edit the article inappropriately. If you’re concerned about using a Wikipedia article as the authoritative voice on a topic, try checking the “Further Reading” and “External Links” sections on the Wikipedia page. They may yield content from a more “reputable” source.
Youtube videos may be linked from the sidebar of a page. If you’d like to embed the video in the body of the page, contact the owner of the video and request permission to republish it. Streaming a video through Youtube is not a good idea because many schools block access to the Youtube website.