I agree with Bill as far as what I would like to see personally, but I don't know how many of those video's they'd sell (but I could be wrong). I play primarily in open D, and the only instruction out there that I could find was the Kelly Joe Phelps DVD. I'd say you should try to fill a different need with your video.
The first step would be deciding what audience you're going for. The way I see it there are three good options:
1) A basic "beginning dobro in open D" that covers mainly bluegrass playing, but in open D rather than the standard G. The downside of this is that many people looking for open D instruction are beyond the beginner stage and looking to expand into open D, but for those that are just starting out and looking for open D instruction (such as people who are using a standard guitar with an extender nut and can't put the instrument in dobro G), or those simply wanting to add open D to their arsenal and learn basic rolls, scales, chord patterns, etc. this would be very useful. About a year ago I’d have loved a book like this.
2) A beginners open D book that focuses less on bluegrass style rolls and more on a fingerstyle approach to playing. I say "beginners" because there is already a video out there that focuses on open D in fingerstyle that goes in to more advanced technical and theoretical playing: the Kelly Joe Phelps DVD. I love that dvd, and it's the only thing out there for open D right now, but when I first got it I was completely lost. Only after i'd been playing lap style for 6 months or so (mind you, i'd played guitar for 6 years and done a lot of work in open D on bottle neck and regular fingerstyle guitar) did I go back to that video and find it very useful. So a beginners book in this style would have a niche, but an intermediate or advanced one would just replicate the only thing already available.
These first two both assume a beginner’s level and would have to focus on the basics of the tuning as well as technique. The other option would be for more advanced players that have experience playing lap style guitar or dobro, and want to expand into open D. For this I’d suggest something like Bill said, that goes into a little more complex theory. I'd say start out with the basics of the tuning (major, minor, pentatonic, and blues scales, chord patterns, etc.) and then move quickly into some more advanced stuff. This type of instruction would also be great for those who already play some in open D for blues or bluegrass, and want to take their music to a few new places.
I think any of these three approaches would fill a need for a good number of players, but personally I’d love to see something more advanced and theoretical, going into minor keys, gypsy jazz, swing, etc. in open D. I would buy a copy as soon as it came out.
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