I'm reminded of a behind the scenes green screen shot with Padme getting out of a car. Only the "car" was three green boxes and, the rest of the "set" was one room of green. I don't see why they choose not to build the transports that they're supposed to be in. Then, I'm reminded of a comment I read about George Lucas basically saying that he pushed himself to do more then a shy person could do. Hence, saying that he was shy as, well. So mabye the reason he uses all this green screen stuff and, tries to make the actors go "faster and, more intense". Is because he's shy and, wants to not have to direct the actors for long periods of time.

In regards to the CGI in TPM you can see a leftover of the cue that Liam got in Watto's shop. When he says "My droid has a read out of all we need." You can see him turn like he was told Watto would be there. This is purely my assumption though but, it sure does look like it. It's funny that in the documentary he worries about Jar Jar's eye's going forward but, not that the shot is un-needed in the scene.