I admit I have never scripted the screencast I did for clients, just laid out the key items on paper and stuck it to the screen to keep then in mind when actually doing the screencast. I am not "natural", I prefer writing to speaking (even in french).
Yeah subtitles won’t cut it, it would simply negate the benefits of a screencast.
Great idea about the voice over thing, how did I not think of it ?!?
I don’t mind inflicting my french accent on you but I’ll do some trial first. I’ll do a test batch and submit this... or maybe ask
edge (Dave Edgerton) since we had a 45 minutes chat on the phone a few weeks back : he can testify my spoken english is rusty !
It’s funny that I can write english just as fast as french (nor nearly as fast) without looking for words but actually doing the speaking makes me slower

And keep in mind it’s always easier face to face to understand a non native since people can (subconsiously) read your lips.
Anyway, if we are to work collectively, one of the first thing to do is put up a list on a wiki page for example and someone signs up for a given screencast. One thing I noticed is you have to keep screencast short. At first I explained several features to my client and then I have split screencast one feature -> one screencast. It makes it easier both for the viewer and you. If you need to do it over, at least it’s not a 15 minutes screencast to re-do. Plus, you are less likely to loose focus or go too fast.