To Embed a Video in Canvas 
When the module or page is open in Edit Mode, click on the icon that looks like a "Play" button on a piece of film
In the box that comes up, click on Embed and paste the "embed" code from youtube and click "OK"

To get the "embed" code from youtube:
Find the video from youtube you want to embed. Under the video, click on the "Share" button
Select "Embed"

In the box that comes up, scroll down to the "Embed Options" section and check the "Enable privacy-enhanced mode" box. 
After checking "Enable privacy-enhanced mode," scroll back up and copy the embed code at the top of the "Embed Video Box." This is what will be pasted into Canvas (or Nearpod, etc)