I don't think it's really about the tricks though, more the concepts and lessons - and my point is simply that many of these are not to be found in DVDs. If someone made a DVD copy of every single Vernon book in DVD format, taught by him and containing all the concepts in the books, by all means, I'd say that go ahead, learn from a DVD. But this for obvious logistical reasons is not possible.
I'd add for your questions about musicians, painters, sculptors and actors, that magic is a different art (if an art at all, which I won't debate here) to those. You simply can't learn piano from a DVD, you can't learn music, you have to read the music, there's no other way. You have to read the music first before memorising it. Painters and sculptors, without personal experience, I would say depend much more on personality and style for their expression in their respective art forms; this is not something that can be taught from a DVD.
As far as acting goes, from personal experience, DVDs can certainly teach you things. But to some extent I think acting is a natural gift; it can be cultivated, certainly, and prodded and prompted, but only so far. To be honest, the limited types of teaching that an actor can undergo must be done in person, simply due to the expressive nature of acting. Then again, we can read about acting styles, but we don't really learn from books, either. We might research something to inform ourselves, but that's about it.
But no, I don't believe that they debate about these things.