I haven't thought of a revenue model yet: just throwing the idea out to see if that's something people would actually like. Getting developers to share their work environment would indeed be a challenge. Perhaps, a karma system a la StackOverflow/HN could be used as an incentive. Developers on StackOverflow don't mind helping each others out so I don't see why it wouldn't work with my proposed format. I have to admit though that making a screencast is time consuming and the karma incentive might not be enough to balance.

Another option that was mentioned in the comments was to ask "celebrity" developers to share their workspace. Celebrities usually like free publicity so I believe that might be a viable option to start out.