I probably misunderstood you about the video analysis part. I thought you were describing a masterclass where everybody watches a one-time analysis of one student by the master teacher, and everybody goes home and can magically improve their playing. For the student who has had his playing analyzed, he might need one-on-one work afterward with a teacher, because knowing what you're doing wrong, and fixing it, are two different things.
In my on-line experiences there have been things of similar nature, and since the work involves sending videos when you're not working live, you really do get to see these things. Among the things that were pointed out to me at various times, not all by the same teacher:
- when I stopped at every note I played in a kind of stop-start-stop, and to aim for a continual flow-through even when the notes was held. This made a difference, and it did not involve someone needing to move my hand or shape it
Other things are harder to describe because they happened in real time, where the teacher says "do this" - you do it, he observes, based on what he observes he has you do something else, and your playing technique improves.
The comment about assuming the studio teacher is competent is true, but it works both ways: why should one assume the online teacher is competent?
One should not assume that either is competent. More importantly, one should not assume that a studio teacher is competent and superior, and that is a trap right there.
The thing is that one cannot always find a good teacher locally, and sometimes, not any teacher at all. One thing about the on-line teachers who are in platform environments, is you will also see how they handle the playing and problems of other students. This can give you insights into your own difficulties, but if you have any experience, it can also give insights into the teaching. I got burned some years ago.
I suspect that a considerable number of pupils are in effect handicapped by starting teachers who leave them with "learned" suboptimal hand positions, and who consequently reach a certain level but can't progress beyond it because they can't play scales, arpeggios, octaves or whatever types of technical figuration without stress or beyond a certain basic velocity.
Yes. And sadly they won't know the cause of this, and think it's because of their own "lack of talent".
I was probably lucky in that my initial teacher left me able to acquire these with minimal difficulty (I was by no means a prodigy in any conventional sense but could play the Waldstein, Appassionata etc by 15).
That is indeed a fortunate thing. Btw, Menuhin said somewhere "If a teacher does not harm his student along the way, that is already a good thing."