Anyway, for those of you who want to modify Movie Maker's auto-event handling, or those who want to remove it entirely (although I don't think it does any damage to leave it attached)---
\WINDOWS\inf\moviemk.inf contains the registry settings configured during the original install. The AutoplayHandlers associated with MSVideoCameraArrival contain pointers to the default app that should launch when a camera is detected (it assumes you want to record). You can remove the handler entirely, but you could set it to point to another program, assuming the target program can handle notifications.
Messing around in the registry can be dangerous, so make sure you have a backup and know what you're doing before you modify anything. ~Apex1x
Miller's Law:
You can't tell how deep a puddle is until you step into it.