Thank you, Markojp.
JASP--with all respect, I too am curious as to your intent with your "anti-video" (at least, that's how it appears to me) stance. Knowing you, I suspect that there is something on your mind that is real and pertinent, but I'm afraid I don't quite get it yet.
You are right, of course, that as instructors, the more we can learn about someone, the better we can help--the more accurate and complete our understanding of "what's going on," as well as what the student's intent, background, and goals are, the more relevant our analysis and solutions.
But surely, you'd agree that a skier's perception of what he is doing very often differs--sometimes dramatically--from what he is actually doing. I'm sure you'd also agree that, as Weems has often pointed out, "words are a terrible way to communicate." So, for example, when someone says "I am carving," or "I move my body forward to start a turn," or "I understand that I should try to move my body forward to start a turn," or comments on just about any other technical point about what he thinks he's doing, or what he understands, the words can be extremely ambiguous. Without further exploration and confirmation, my (or your) interpretation of the words may paint an entirely different picture than what the speaker meant.
And then there's the "VAK" thing (visual-auditory-kinesthetic--different sensory channels through which we gather information and understanding, and of which some people prefer one or another channel over the others). Leaving any channel out leaves a big hole in the picture.
No one has suggested that it isn't important to explore a student's personal understanding, or to learn more about a student than we can learn just by watching. But watching a skier, either live or, often even moreso through video (because we can "rewind," freeze frame, slo-mo, and so on), certainly adds to our understanding. Yes, video is "2-dimensional" (usually), but that hardly suggests that it isn't an accurate portrayal of what the skier actually does (or did on that run, at least). Yes, varying camera angles can reveal even more. But nothing else can "show" us the skier better (except sometimes a live look). Vince Lombardi famously said, "you can observe a lot by watching." Do you agree? Or do you think it's a waste of time? I submit that only when we cross-check the student's understanding against a good visual does the "exploration" of understanding become an accurate "assessment" of it.
Your concern about video being only 2-dimensional surprises me. Would 3D video be that much more useful? Does a one-eyed instructor waste his time watching students, simply because he lacks stereo vision? Do you really think we cannot learn from a 2D video, or that what we learn from 2D video is likely to deceive us to the point that it is not worthwhile? I know you, and I don't think you do mean that, so I have to wonder why you replied so negatively to Kevin's suggestion that video could be helpful.
You plea for the need to learn more about a student, and I don't think anyone would disagree. I suggest that video tells us two critically important things. First, it shows what is really happening--what movements actually take place, what technical skills, adaptability, and movement habits the skier possesses, along with, quite often, shedding light on the skier's intent and understanding (or misunderstanding). Second, it shows how closely aligned the skier's understanding and perception are with "what is really happening." Without these critical insights, we can listen to and read the words of a student all day long, but our understanding of the skier will still contain a huge hole, and any "advice" we give will be based on assumptions and beliefs, rather than facts.
So, when KevinF suggests (in post #23, after considerable discussion based only on what the OP wrote), that some video might be helpful, I must question why you would not enthusiastically agree. I think it's unfortunate that your surprising dismissal of Kevin's suggestion has nearly derailed what had been a pretty good discussion. Your suggestion that well-meaning posters had "barfed generic advice on his shoes" is pretty offensive and non-productive--especially in light of it being a response to one poster's earnest attempt to learn more about the student (through video). I hope we can get it back on track.
JASP--I hope that I've read your words wrong, actually, and that you intended something more productive than what has transpired. I think most of us have a lot of respect for your experience and understanding. I certainly do. At the very least, if we've misinterpreted your words, it demonstrates strongly why just reading someone's words can badly miss the point!