The Igloo editor is capable of dealing with a wide variety of embedded content, but sometimes it comes out looking a little like this, a big blank space:

Far from this being an Igloo bug, it is a carefully considered and implemented feature of your browser. All modern browers consider unsecured content on an SSL enabled site to be a security risk and actively blocks it from running. 

Fortunately, many of the video and other content hosting sites that thrive on shared material are aware of this and provide secure protocol options. In most cases, all you need to do to is add an "s" to your embed link.

If embedded material is not appearing, as above, then go into the source editor (the <> button) and check to see if your embed link starts with HTTP or HTTPS. If lacks that "S," just add it in and the content will probably render. 

If adding the "s" does not fix the problem, then the hosting site may not provide HTTPS support and, for your protection, your browser will refuse to render the content on SSL enabled sites.