Here are a selection of useful resources for learning more about Drupal 8. I've found them useful.
Good Features presentation from Drupalcon LA 2015 by Mike Potter of Phase 2
Matt Cheney video on Configuration Management CMI - Drupalcon Los Angeles 2015
Alex Pott on Configuration Mangement CMI (deep dive with coding) at Drupalcon Barcelona 2015
The session starts with an overview of how configuration management fits in to Drupal 8 before becoming a technical dive into the features it gives the developer. Answering questions like "What is a configuration entity?", "What's a schema?" and "Optional configuration, what's that?" the session will give the audience technical information on how to use the system. The session concludes with the advanced topic of configuration dependencies and how they are used to make Drupal 8 robust and awesome.
Greg Anderson article on Configuration Workflow CMI using config-merge
Larry Garfield Drupalcon LA 2015 Drupal 8 crash course.
Walkthrough of Drupal's key systems and APIs, intended to give developers a taste of what building with Drupal 8 will be like.
GraphiQL on Drupal bySebastian Siemssen
Larry Garfield (Crell) on D8 dev - Drupalcon Los Angeles 2015
walkthrough of Drupal's key systems and APIs, intended to give developers a taste of what building with Drupal 8 will be like.
More Barcelona 2015 Drupalcon videos to watch about Drupal 8
Drupal console deep dive with Jesus Olivas
How to use composer, incl how to install a php library in drupal (14 minutes)
Drunken Monkey Thomas Seidl at Drupalcon Barcelona 2015 presentation on search api
and a more recent version (Mar 2016 - without audio: )
Acquia Drupal 8 training course "Building modules with Drupal 8"