It is always nice to include images and video clips within your text. Fortunately there are literally millions of openly-licensed objects that you can use for this purpose without having to seek permission or pay for the usage rights.
A good place to start with looking for images is the Creative Commons search engine, which searches the Creative Commons sections of Flickr along with the Public Domain-licensed collections of the Metropolitan Museum of Art, the New York Public Library, and the Rijksmuseum. Another website with excellent public domain images is Unsplash.
YouTube remains the best place to search for video clips. However, few people are aware that among the filters available is one for video clips that have adopted a Creative Commons license.
As a bonus, YouTube even has a built-in editor that you can use to copy, download, trim or otherwise revise these CC-licensed clips.