The McNab instrucional snowboard DVD (Go Snowboard) is very good, it's excellenty priced and comes with an accompanying book. Perhaps non-beginners may find it more useful than those just starting out, but if you're in the market for instructional guidance, I'd recommend this.
Who's it for?
In my opinion the terminology and demonstration used for beginners is a little over-complicated. Pressure control, edge control, steering and using opposing pressure seems a little much to begin with. Too much to think about. I get the impression that it will mean more to you once you know how to ride...
A rider comfortable with the basics, an intermediate, or a more advanced rider on the other hand, will be able to think about and practice the techniques discussed, as they won't be concentrating so hard on simply not falling over. These techniques, I beieve, are excellent. "Turning the board by design".
So I'd say that the DVD covers a wide range, but I'm not 100% sure about absolute beginners. The DVD certainly made a positive impact on my riding.
Go Snowboard broken down
That's not to say that there is nothing of use for beginners. Far from it. To begin with the book is excellently produced; great pictures and great layout. The book supports the DVD and the DVD supports the book. The book includes a lot of good off-the-hill information in there that will help you get started.
The stance, body posture and your first movements on the hill shown to beginners are also good. The regulars: slide slipping, diagonal slipping, falling leaf are all included... I just think that too much emphasis is placed on how the board works, too soon. Maybe I've got it wrong? Maybe the beginner should focus on precise manipulation of the board from the start? My current thinking on this however is: get comfortable with basic linked turns, build a little confidence, then start to refine your technique.
Intermediate riding - this is where I believe this instruction comes into its own. Controlling the board throughout the turn by applying the correct pressure at one of the four pressure points, at the right time: the McNab pressure control system. I was definitely missing out on some required pressure at the rear of the board later in the turn. Straight away when watching the DVD I knew this was something I needed to try... following this method made my lines much tighter.
The DVD covers some useful techniques to help you become in-tune with how you're really interacting with your board: pointing at the pressure control points and riding with your hands on your knees. There are also exercises to help you refine you skills: "counting", the "funnel" and the "corridoor". They really are worth trying out.
Advanced riding. From the whole DVD I was most interested by a technique called the cross under edge change, where the board crosses under the body as it moves from one arc into the next. This technique is used to control the board correctly on steep, technical terrain.
It's interesting to me because although I feel I can ride with good technique on intermediate terrain, I can't make consistent speed-controlling arcs without pushing edges out on steeper stuff. Following good technique just causes me to go too fast.
It's listed as an advanced technique, which I'd agree with. It's certainly too hard for me at the moment, especially without further guidance. It looks good though and it feels like the way forward, so I'll be working on it.
Go Snowboard also provides a very good introduction to freestyle, short but well thought out. There's good coverage of the ollie and the guidance for catching your first air from kickers is right on.
Similarly the topic of freeriding is only slightly touched: a brief look at how to adjust the pressure control system to work in powder. But that's fine in the context of this DVD/book.
In summary, I don't think you can go wrong with this DVD, especially given the price. It covers a wide ability range, providing good excercises to work on aswell as sound technical instruction that's up to date. Go buy Go Snowboard.