Just to toss in my two cents...
Resolution. I have seen a number of tutorials where the resolution is horrific and you cant see what menus they are selecting, they go real fast and just start switching options without explaining what each check box does, so you cant see and you have no idea what they just changed, but theirs works and yours doesnt. I have a few Gnomon DVDs and I really like that the person sometimes will take a quick prnt-scrn screenshot, minimize maya, and maximize Photoshop, paste the screen, then zoom in on the options and explain them there.
Repeating. Another thing I like in the Gnomon DVDs is that they are great at really ingraining what they are doing into your head. Sometimes they will just undo every command and repeat the whole step like 3 times, repeating what they say and how they did it. Sure it might seem remedial, but it helps slower people, and helps if you missed something, and helps nail in your head how to do something if you want to do it again.
Clarity. Please, if you are going to do audio, speak clearly. Dont have people walking around you, cell phones going off, dogs barking. I have watched a few tutorials where you can hear someone walk in the room, say sorry and close the door behind them. Its just unprofessional. It helps too if the audio is rather high, too low is aweful...you can always turn down a speaker, but turning it up and hearing rough noise sucks.
Chapters. More chapters helps so that you can stop at anytime and not have to sit through a 45 min chapter. One thing I dislike about Gnomon is that sometimes a chapter will be over an hour long...and so I have to either pause it for hours while I go eat, or sleep, or whatever...if it had more chapters I would just say okay I will stop at the next one and pick up tomorrow.
Okay as for specifics. I would love to see how to make tools work for you. For instance changing options in the box to get different shapes, modeling techniques, and increase efficiency. I like learning new short-cuts, things that really speed up my modeling. I like learning how other people put together their hierachies, their scenes, groups, layers, etc. I love learning new shading techniques, using nodes, textures, rendering, lighting, etc.
And of course, when it comes down to it, how long it is, how versatile it is, and how much it is. I would rather pay 60 dollars for something that teaches modeling techniques with various models...than 60 dollars for a single this is how you make a pen. But if your DVD included how to model lots of office objects, or how to get various rendering, or animating the pen writting something. The more broad the DVD the more its worth in my opinion.