Anyone who has ever searched for origami on YouTube will have found increasingly more instructional videos being posted there. Almost always these aren't created by the designer of the model, and I think mostly without the consent of the designer. I am opening this topic in the hope to hear from you what your opinion is on this development.
I'll add my own opinion on this, together with a bit of background as to why I'm opening the topic. But if you just want to comment on the summary given above, that's fine with me. Really, my post did get too long, but I feel I don't want to remove any of the thoughts I presented.
My story / opinion
About half a year ago I myself started creating videos on how to fold specific models. The first was on one of Toshikazu Kawasaki's roses. I'd seen a couple of videos online, and thought they were quite unclear, and - hey- I'd be able to do a better job than that. I uploaded a video without contacting Toshikazu before. The video proved to be quite successful, and I started making other videos. I was happy to see that I could make a difference - promote origami, show others its beauty.
However, with popularity increasing I started thinking about the implications of this project. I came to the conclusion that it was wrong of me to do instructional videos without asking the creators of the models first.
My project underwent some changes. I contacted designers, and asked for permission, also apologising for not having done before putting the videos online. Most designers gave me permission. I won't pretend there wasn't critisim in some of the responses, but that was much deserved. Within this process I also changed my videos slightly, trying to state as clearly as possible who the desinger was, and adding the prefered resource for diagrams.
I think now my procedure runs relatively smoothly in that I first contact the designer, and only if I receive permission I will create a video in the first place.
Because of this development, some of my videos aren't available anymore, though. I haven't been successful in contacting some designers. Unfortunately, Toshikazu Kawasaki is one of them.
However, there is also one case in which I successfully contacted the designer, and she disapproved of my vidoes. This concerned Valerie Vann and her much appreciated Magic Rose Cube. She has a quite strong view on not wanting any kind of instructions (diagrams, videos, etc) for her designs published on the Internet. I respect her opinion, and think I have an idea of what her reasons for this are.
However, there are quite a few videos showing how to fold her MRC on YouTube (and the such), and some online diagrams. When I leart of Valerie's feelings on this, I felt very bad about my video. I removed it immediately, and some time later decided to contact others who had been posting videos on her design. Most of these comments were ignored, though I think one or two users did remove their videos on her design.
So this gives us the following situation:
1. There ARE instructional videos available.
2. Many designers might not be aware of them.
3. Most designers will not have been asked permission for them.
4. Some designers do not agree with these videos.
While the first one is not necessarily bad, I do think the following three are not desirable. In September 2007 I visited my first convention, and feel that is when I joined the "origami community". Since then I have again and again experieced what a warm and welcoming lot you all are. It surprises me still now, and I am very grateful for what I have found through this. Indeed, by making my videos I want to give back some of what you have all given to me.
But this is in such a strong contrast to what seems to be going on with instructional videos. I don't think there are bad intentions in most cases, but I also think often the respect for the work that's involved in designing is missing, or not strong enough.
I do think that instructional videos can help to promote the designers, and actually motivate more people to buy their books etc. I do think it can help promote origami in general, and that in itself hopefully profits designers. But I don't think there is enough awareness of the "right way" to do this.
I still am not certain what the right way is. I am not sure what copyright says, especially in different contries. I am under the impression that in some countries these instructional videos, if created without permission, violate copyright law, and in others it doesn't. There is also a difference between commercial and noncommercial use. Most importantly, though, I think the ethical aspect should considered. No matter what law says, there is a "honour codex" that everyone should follow.
I'm not saying I'm perfect. After all, I told you my story and how I started in a way I now think was just wrong. This was mostly because I didn't think it through first, as you always should. But I did change my ways, and I guess that's at least something. While I don't expect everyone to agree with me in these points, you will probably have noticed that I have thought about this topic my fair bit. The painful length of this post might be the most obvious indication.

Summing up
So I just wanted to get it out there. Hear what you think. If you have hard facts on copyright, I'd love to hear them. But very much I'd also just like to get your opinion on this in general. Instructional videos, should they be created, what's the right way, and are they any good in your opinion anyways?