I recently came across eosacro’s introductory videos for Nuke that take you through a basic introduction of Nuke, and Nuke’s interface and basic UI and also a bit about how Nuke handles images and channels. I have a suspicion that there may be more of these, so I may update this post as they become available.

If you are new to Nuke or maybe just want to look around to see how it operates or how a nodes-based compositor handles compositing tasks, this is a great introduction for all of those things.