This is a nice speed painting video tutorial done by David Holland. Even though there aren't any commentaries this concept art-speed painting tutorial is not spead up so you'll be able to see the workflow. Check out the the entire Jungle waterfall speed painting video tutorial.
Jungle waterfall from David Holland on Vimeo.
p.s. sorry I can't find his portfolio/web page.
Welcome to Concept Art Masters Blog
Welcome to Concept Art Masters.
This blog has been created to help out anyone looking for killer concept art tutorials. This place is a collection of over 100 free tutorials designed by professionals who know their stuff. What this means to you? It means that you will be able to maximize your skill level in a shorter period of time without worrying if these concept art tutorials are of any quality. Why pay so much for expensive art schools when you can get almost the same results for free.