All embed codes are HTML, so you'll need to click the Switch Views link in the upper right above the page you're editing to insert them. Canvas has great guides on embedding videos and iFrames in pages; the same principles apply here.

You may need to refresh the page to get the widget to display.

YouTube videos can be added simply by pasting the videos URL into the page, then saving.

Do you want to use reading lists from the library databases (OneSearch) inside of Canvas? Don't download PDFs or copy and paste articles, try OneSearch: Curriculum Builder which allows you to build readings lists seamlessly and track who does the reading inside your course. Here is the documentation on how to use it:

If you have any questions about using OneSearch Curriculum Builder, contact one of our librarians.