Embed YouTube videos

1. Get the YouTube id.

   Example: The URL is https://www.youtube.com/watch?v=rWkVS9qxBmg.

   The id is the text after v= and up to the next & or the end of the URL.

   Here: rWkVS9qxBmg.

2. Embed the Video using the id

   2018-01-19 by Mathias Schreiber
   
   ..  youtube:: wNxO-aXY5Yw
   

   How it looks:

   2018-01-19 by Mathias Schreiber