Timing video capture

[slotcarbob]

This is driving me nuts, and no one is actually saying it can't be done. I have an ADS Pyro link to capture video into iMovie (Or QT Pro). What I want to do is set up anything that will start a capture at a specific time, and then stop it at a time I say (or so many minutes later, whichever). I stink at using Automator, and can't write scripts, so any help would be appreciated. Thanks.