Screencastify is a powerful tool for creating video tutorials on the fly.
This is a chrome extension however you can either use Screencastify to record just a tab or your entire desktop!
Here is a short Screencast on how to add and use Screencastify:
You can find and install Screencastify from this link: https://goo.gl/ADPjQ4
If you have any Questions or Suggestions, follow this link here: http://goo.gl/2mTkUU