its some ILM'ers playing with footage on their lunch breaks and if lucky enough what they do gets shown to george on occasion and then if its passed by him as a "neat little idea" i.e. hayden as a ghost its a done deal or at least thats how it was done around the time of the dvd's (a little fun fact the footage of anakin as a ghost was actually shot and scheduled for the episode 3 shoot it may look like a simple outtake was used but actually took a while to setup and shoot! and still ended up looking like it was done by an intern on a lunch break)