Use Hazel

I'm wondering if anyone has any bright ideas here. The short version is that I'm wondering if there's any way to Hazel do anything to a file that's "busy" but I suspect there isn't.
The long version is that I'm using Hazel as the basis for an automated encoding system that allows instructors at my university to make recordings and have them automatically encoded and uploaded to our online video delivery system. The instructor remotely activates an AppleScript that starts recording (via Vidi if you're interested) and another AppleScript that stops recording. Hazel watches the recording folder and looks for files that haven't been modified in the last ten minutes and moves it to the encoding folder where all manner of other things happen via Hazel.
The problem I'm running into is that from time to time, an instructor will turn the recorder on and then walk away with it still running so that it fills up the hard drive entirely. So I'd like to limit the recording length. Any suggestions on how I might do that? I tried creating a rule that would activate the "Stop Recording" AppleScript once the file got to a certain size, but log reports that the file is busy, so it's being skipped.
So am I correct in thinking that I won't be able to use Hazel for this? Any suggestions (Hazel or otherwise) are appreciated.
The long version is that I'm using Hazel as the basis for an automated encoding system that allows instructors at my university to make recordings and have them automatically encoded and uploaded to our online video delivery system. The instructor remotely activates an AppleScript that starts recording (via Vidi if you're interested) and another AppleScript that stops recording. Hazel watches the recording folder and looks for files that haven't been modified in the last ten minutes and moves it to the encoding folder where all manner of other things happen via Hazel.
The problem I'm running into is that from time to time, an instructor will turn the recorder on and then walk away with it still running so that it fills up the hard drive entirely. So I'd like to limit the recording length. Any suggestions on how I might do that? I tried creating a rule that would activate the "Stop Recording" AppleScript once the file got to a certain size, but log reports that the file is busy, so it's being skipped.
So am I correct in thinking that I won't be able to use Hazel for this? Any suggestions (Hazel or otherwise) are appreciated.