I have been adding some new content here (mostly following along with the elementary introduction book and doing explorations in machine learning):

https://www.livecoding.tv/learn/wolfram/

These 'live coding' sessions are recorded so you can watch them. They are a little bit different from pre-recorded video tutorials, because there is a chat window where 'live watchers' can ask questions (which you can not do when you watch the recording, of course).