External Content is embedded in the site in one of two ways:

Embed using Code

Obtain the embed code from the page you want to embed. This is the best way to embed Twitter or Google content.

Once you've copied the code from the host site, click on the Edit HTML Source within T4's All Purpose Content template and paste the code into the popup window.

Embed by URL

Paste the link to the page into the content area. Select it, and in the styles dropdown above select 'media_embed'. This will surround the content in a grey box while you're working on it in T4.

When the site publishes, the Video or Photo gallery will be included in the page. Many, but not all popular media types are supported and for security reasons some will not be visible in Preview Mode.