I got into this argument with a person who has taught for 27 years. I have taught for 27 years he said. I replied I looked at the best in the world on a tape for 5 minutes. And I can tell you which is right and which is wrong. We can all play in slow motion or frame by frame. All we need then is to know what we are looking for.

By a strange coincidence i have been lecturing in a technical subject for 27 years. I don't know what your level is, so my comments may be inappropriate, but i don't teach the same material to first or second year students as i do to fourth year students. The good basics i teach in first two years makes it much easier for them in 4th year. Learning is a tricky process and sometimes you have to do it a step at a time (sorry about the pun!). The best exponents in any sport don't follow the rules - but they know exactly what the risks and trade-offs are and they started at the basics level. If you try to follow the experts from day 1, things may not work out as you want them to.
Take the advice of your teacher. If you don't want to, then drop him and just use the tapes. But you will find that different tapes will show you different things.

The "best in the world" often break the rules to get a particular effect or adjust to their own particular bodies. They can get away with it because they have such superb control of their bodies they can create whatever kind of movement they want to.

Also, the idea that there is only one "right" way to do something is false. There are different schools of thought about some technical points and also techniques have changed and evolved aver the years. If your teacher is teaching the way he was taught 27 years ago and you are looking at recent champions, they both could be "right" for the time period they are coming from.

Technique is not an end in itself. The only purpose it serves is to create beautiful movement. The techniques that are called "right" are those that have made it possible for most people to create the best movement. Soemtimes a champion invents a new technique that helps him/her achieve the look they want and then it is copied and becomes the new "right" technique.

Ellen, I agree with what you said here.
So, all of us should keep learning and welcome the development.

I try to watch a DVD but each separate part. This can be difficult. It is a bit like a conjurer who moves one hand which we find imposible not to follow, whilst the other is setting up the trick. So I block out the top line and the feet and today checked the amount of bend in the knees on a Feather and Reverse Turn into a Wave. Does the leg between the hip and the knee bend to an angle of 45 degrees. And between the knee and the ankle is that also 45 degrees. how do we get to at the extent of the stride on two straight legs to repeat. Its all there for the looking. One of the German couples on the first step of a Reverse Turn in the Waltz. The rear knee would be within 10 to 12 inches off the floor. To get the strength to do this will always beyond me. But at least I know its there.

someone who answers questions with the claim that they have been teaching for 27 years must be quite insecure

That's a nasty little comment. I only mentioned the 27 years bit because of the coincidence, as i made clear in my posting.
At least i use my real name, unlike yourself who doesn't have the security to put his/her name to anything

you totally miss the point. if the teacher knew anything and was interested in teaching it, they could come up with a more convincing explanation than expecting to be believed simply on the basis of the length of time they've been teaching