To place an embed (such as a YouTube video or Google Map) onto a page, simply copy the full URL of the content and paste it into the content editor on its own line. This is as opposed to copying the actual embed code or the short URL and pasting it in.
Correct Embed Example: Full URL
https://www.youtube.com/watch?v=WIHFjz3d4uE
Incorrect Embed Example: Embed Code
<iframe width="560" height="315" src="https://www.youtube.com/embed/WIHFjz3d4uE" frameborder="0" allowfullscreen></iframe>
Incorrect Embed Example: Short URL
https://youtu.be/A-4dIImaodQ
See the below image using a Facebook video as an example:
What If You Can Only Use An Actual Embed Code?
If you must use an actual embed code, you can paste it into the page's Template following these instructions.
It's best to use Basic type pages for this purpose, as their templates make it easy to paste in the embed code.