When my friend Tom stopped over the other day I showed him a time-lapse video (that seems to be by someone using the name Design—I can't see any other names even on the "about me" page) of a Photoshop illustration Danny Gregory had recommended.
After Tom and I had watched that Tom had me jump over to the video that starts this post. It's a Photoshop painting by Lois van Baarle. (Be sure to watch the second part as well to see where she ends up with the painting.)
I love both these videos first because the artists are obviously very talented, but second because you see in quick fashion the many little decisions each makes as their paintings progress. You'll see them redraw, rework, rethink. Creating a painting, whether digitally on the computer or with natural media on paper (or canvas or some other substrata) is a process, and sometimes the process changes in midstream.