Salesforce recently hosted their annual developer conference, called TrailheaDX '17. The Salesforce Developers Youtube channel has posted a playlist of 138 videos from this awesome event.

The playlist is full of 40 to 60 minute video sessions and presentations. You'll see a lot of mentions of Einstein and Lightning, throughout. Here are some of my favorite videos from the list:

Einstein - Adding Intelligence with Deep Learning

Org Security Fundamentals

How to Set Up Checkout to Sell Your AppExchange App

Build Your First Custom App on Salesforce

Lightning Sales Console

I hope you find something helpful in this list of free resources. Happy learning.