All right, once again, my two cents -- for whatever it's worth!
I went through your entire tutorial (Hey! It's not done yet! There's a cliffhanger at the end!), and I still think my personal favorite is the text version with screenshots. I'm not saying that the videos would not be helpful -- but not only did these go off of my screen and cut off the view of what was happening, but they were very fast, and I missed what you were doing (not helped by the missing portions, I think!).
I think that in a text-type tutorial, one could assume that the viewer has some basic skills with the graphics program they're using (PS, GIMP, etc.) and some of the screenshot examples could be left out -- things like 'create a new layer and name it 'Water Texture' and other such basic instructions -- thus cutting down on the number of screenshots you'd actually need to use.
Not that I want to make things hard for new users!
For part of your tutorial I went along in Photoshop and found your instructions pretty easy to 'translate' from GIMP. I wonder if it is possible or practical to author some of these tutorials with a partner who uses the other program, making notes of how the procedure would be performed (or if it is not available) in that other program.
For instance:
What if you want to see the image without the layer mask? You can temporarily disable a layer mask if you like. [In Photoshop, Shift-click on the layer mask thumbnail in the Layers Palette. A red X will show on the layer mask thumbnail.]
And here's another totally outrageous idea... There are some tutorials that I like to refer back to frequently. How about providing a downloadable (PDF) version I can keep forever and ever and ever??
I know. I'm making MORE WORK. I'd actually be willing to help out some. I'm a pretty good editor, and although my PS skills are hardly up to professional quality, I'd be happy to try to fill in the PS equivalents to GIMP commands.
(And I'm probably up to about 25˘ now, huh?)