You can have text appear above and below an embedded YouTube video.
As I'm typing this, I am in WYSIWYG mode; The text I see can be formatted, and I can add descriptive copy about the video content.

When I get to the point where I want the YouTube video to appear, I click on the SOURCE button to switch to html mode, and paste the code in:

Then I click the source button again, and continue to write the article in WYSIWYG mode.

Save your changes when done!