Jakub ‘jimmac’ Steiner has published several demos of the GIMP in action.
Subjects such as defining shortcuts, image templates, transformations and paths and more are covered. Use the mirrors, because I haven’t downloaded the videos myself yet!
Except where stated in the post, photos posted on or after January 1st, 2014 are licensed under a Creative Commons Attribution-ShareAlike 4.0 International License. Basically, do what you like with those images but always credit Donncha Ó Caoimh as the author and link here. You'll also have to license the photo under the same license.