I used to work at Universal at the now removed E.T. ride
and used to see these tour guides whisk these people in the back door of the rides and thought that they were either celebrities or friends and families of celebrities. Later one of the tour guides told me that you could purchase special VIP tickets to get those special privilages.
Since you're going in August it might be worth it to you since you bypass all the lines and go directly into the rides and shows. Plus being that it's on a Wednesday and in August a lot of TV shows will be in production by then, if you wanted to catch a glimpse of celebrities. I remember during the summer time a lot of celebrities would go through the VIP entrance on a lot of the rides. That would be where you would be entering too I imagine. Though with the advent of the "fastpass" type of system they may have changed things.
If you're a big movie buff, it would probably be worth it if you could afford it. Spider-Man 2 and Van Helsing with Hugh Jackman are being filmed at the back lot right now, but I'm not sure if they'll still be up by the time you go. But usually August is a very busy time for a lot of productions so it might be worth your while. And since you're with a personal tour guide, some of whom are very friendly with the celebrities, you might get a chance to meet someone. I used to see a lot of the celebrities with their famileis or by themselves being escorted around the park by the tour guides in the same vehicles you'd be going on. Just make sure you do it in the early morning. Most of the filming is done in the morning or at night. Productions usually wrap by noon and don't come back til later in the evening.
