When adding a new External Content tab it is possible to embed content from a website or YouTube.
iFrame
To load a website directly in a tab, enter an embeddable URL in the iFrame field. Please avoid using standard website homepages or top-level URLs for this purpose, as most sites block this for security reasons, which may cause the tab to appear blank or function incorrectly.
YouTube Video
To display a YouTube video, enter the unique Video ID found at the end of the video's URL. Please note that if a user has not accepted third-party cookies in their browser, the video will not load automatically. Instead, a cover image will be displayed that allows the user to accept YouTube’s terms of use to view the video.