Yay! for another GIMPer starting a youtube channel.
Camstudio doesn't let you drag layers. The expensive Camtasia studio has the same problem. You can get around this by explaining to your audience how to drag the layer and then use the arrow buttons in the layer dialog to reorder the layers. I usually solve this by pretending to drag the layer and then say, "But you can use these arrow keys as well." and then I use the arrow keys.
I foresee problems with layer groups but if/when the problem arrives I'll just stop the recording if I need to drag in groups and stitch the separate recording together in editing later I guess.
The things is, camstudio gives you excellent results. Just as good and sometimes better than camtasia. Especially if you use the the camtasia codec, that is free, with camstudio.
About doing written tutorials? Ask the tutorial maker for permission and if it's hard to track them down as least credit them fully in the video itself so it's always clear even if the video gets embedded on another website then youtube. But please consider making your own tutorials as well. You'll increase the GiMP resources that way.
p.s.
Be prepared for hate comments. Youtube is too anonymous for some people to handle and they say things that I can only explain as either bad puberty or them taking out some frustration on you.
You need to have a thick skin. And you need to be able to recognise the difference between constructive criticism and plain rudeness.