In the US, even if the material performed or taught is not copyright protected per se, recording and distributing it without permission is, I believe illegal. We had a court case in our area about a university professor's conduct in that area. I believe he recorded and then reused material from a workshop he had attended.

Even if the presenters ere fine with on-site recording by participants for their own use, I think the right thing to do would be to make the project available to the presenters, and ask them to OK what you do. They may see it as a fantastic resource, and an opportunity to extend their work, and since it IS their work shouldn't that decision be up to them?

~Susan