This feature is only available with the following products:
An HTML page can be used to insert code for embedding widgets, google pages (pdf, sheets, docs, maps), videos and more.
For instance, you can embed videos from YouTube on an HTML page. Or you can embed weather widgets, driving directions, Google Maps, and so many more widgets.
For instance, in the sequence above, we are adding a YouTube video by copying the embed code from YouTube, creating the HTML Page, and pasting the embed code.
Notice there is a preview below the code to ensure you are pasting the correct code.