Hi,
So... a Mac Mini with an External Logitech camera using Photo Booth with Backdrops and Effects and then selecting a Backdrop option.
The Messages should come up from as long as Photo Booth detects movement.
If you stop partially out of the pic that portion of you may display in an odd fashion.
I presume you are saying that Photo Booth is not giving you time to move out of the Frame.
From there I presume you get this sort of thing
It might pay to delete the com.apple.PhotoBooth.plist
I can't see this holds a timing item in it but some standard settings don't show when using Property List Editor.
Have the Finder as the "Front" App
Use th Go Menu
Whilst in Drop down hold the ALT key
Select the Library that appears
In there open Preferences
Find the listed .plist and drag it to the Trash
Restart Photo Booth.
10:25 PM Sunday; September 2, 2012
Please, if posting Logs, do not post any Log info after the line "Binary Images for iChat"
iMac 2.5Ghz 5i 2011 (Lion 10.7.2)
G4/1GhzDual MDD (Leopard 10.5.8)
MacBookPro 2Gb (Snow Leopard 10.6.8)
Mac OS X (10.6.8),
"Limit the Logs to the Bits above Binary Images." No, Seriously