I have not had time to make new videos, but all of the tutorials on the channel are still valid. I recently remade all of the scenes and source files for the Game Development With Playmaker series which was recorded in 2011. They're still completely coherent and easy to follow in the latest version. Also, with all of the videos, any changes in the UI are annotated in the videos whenever we find them.
The biggest thing in 1.8 is that a lot changed on the back end with how it reads and saves FSMs so it can be buggy to upgrade big projects and the new Array and Enum variables are a big addition as well. The rest is fairly minor convenience items, bugfixes and tweaks.