So far, there are three parts of the guide available. Part 1 deals with some of the very basics, but probably the most important section is understanding "commercialization" and what Blizzard's rules about it. A super quick summary of commercialization is "using a product to make money," but you should take the time to check out Myndflame's guide. He's obviously a bit more thorough about the explanation.
Part 2 of the guide talks about Blizzard's Fair Use policy for machinima. I'd consider this guide a must-read for anyone who wants to create machinima. It deals with how Blizzard supports machinimators, but also warns about where you'll encounter the limits of that support. For example, machinima using Blizzard properties should be "T" rated movies -- they don't want Blizzard icons getting mixed up with unsavory subjects. Part 3 of the guide deals with music, which is a key component of any good movie. A good film has to have a great soundtrack, after all.
I think Myndflame's guide is a pretty interesting read for anyone, even if you don't plan to make your own WoW movies. It gives some perspective and analysis to how much Blizzard strives to work with their community, and definitely shows what a vital, thriving society WoW machinimators can be. I appreciate the insight, and the work is a pretty fun read over all.