Embedded videos, widgets, and other multimedia should ALWAYS load via an encrypted SSL connection. Embedding "mixed content" will trigger an "insecure connection" browser alert.
Embed only secure content by ensuring that your YouTube and other embedded links begin with https rather than http: https://www.youtube.com/ rather than http://www.youtube.com/.
Your public-facing guide should display a green lock in the web address bar (examples below from Google Chrome). Each of your pages should look like this:
Not like this:
Help protect the privacy and security of our users by embedding only secure content!