To add a YouTube video to your site you first need to load your video onto your YouTube channel and then grab the Embed Video link.
See Screen shots on where to find it in YouTube
Then follow these steps to put video on the website.
-Edit content of Text/HTML module you want to place the video in.
-Once in the editor click Source and paste Embed Video code from Youtube
-Save
**If the video does not display in the correct dimensions for your website you can edit the module, go into the source again and modify the width and height. (see screenshot directly above as example)