Become a MacRumors Supporter for $50/year with no ads, ability to filter front page stories, and private forums.
I think you could modify this technique that Ice-Cube outlined for adding the hologram effect in this thread:

Hi Guys, I have just figured how to put this effect in Photobooth as well.

1. Extract HoloGit.qtz from the zip file.
2. Place it on your desktop for easy access.
3. Copy the HoloGit.qtz file to /Library/Compositions - The keyword is *Copy*
4. Go to photobooth in your applications folder and right click to *Show package contents*
5. Navigate to content>resources
6. Drag the HoloGit.qtz file from the desktop to this folder.
7. Locate the file *EffectsOrdering.plist* in this folder
8. Open the file with textedit
9. You should see a number of effects listed in that file. You should see user backdrop 1, user backdrop 2, and so forth in the last paragraph.
10. Replace the words *user backdrop 1* to *HoloGit*
It should look like this: <string>/HoloGit</string>
11. Save the file. Close all folders.
12. Open up photobooth and enjoy your newfound effect.

Taken from this thread entry #27
 
Removing effects from PhotoBooth

Go to Library/Compositions, or alternatively, f you have downloaded effects from the web, try /User/your-users-name/Library/Compositions
 
How to Delete PhotoBooth Backdrops

Hey guys, to delete a backdrop you dragged into PhotoBooth, simply click on it as if you where going to use it to take a picture over it, and then press command+delete. And that's it! Hope that helps. Take care.
 
Register on MacRumors! This sidebar will go away, and you'll see fewer ads.