Hey,
just wanted you to know that Sean Kennedy has opened today his new blog about visual effects techniques, tools, and tutorials. All about open and free tools.
I think it will be great for all film freaks to see how a professional works.
So here is the link:
To get the lastes news from the blog, here is the twitter link:
https://twitter.com/openvisualfx
He posted a 2,5 hour long course for Blender and its 2D tracking, also his presentation from the Blender Meetup Day 2016.
Some tutorials for Natron will follow soon.
Its worth a look. 
Thanks for the heads up - followed!