Bob,
I'm a visual learner as well. That said, I would think written instructions would be better. I don't think many people would have a TV/DVD or computer/DVD in the garage so they could watch the video while working on the car. However, everyone would be able to take written instructions into the garage with them.
I can see the best advantage of video being a general education for the inexperienced. For example, pointing out parts so you can associate a part by an unfamiliar name. For example, "this is a Warm Running Device" or "this is the MFI pump fuel mixture screw". I think a lot of new DIY mechanics, such as myself, could learn a lot from a video, but step-by-step procedures are best left to words (along with some pictures/diagrams).
Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both tops
1994 E420