I use Camtasia 2 for recording video on my computer, but there is no way to schedule a stop duration. You can do this relatively painlessly using applescript so you don’t have to set timers and run to turn Camtasia off manually.
1. launch Applescript Editor (Script Editor in Yosemite)
2. Type in this code, changing the delay value to the desired number of minutes * 60:
tell application "Camtasia 2" delay 3600 stopRecording end tell
3. Start the Camtasia recording, then press the play button in the Script Editor.
It’s as simple as that. Now you can record the screen unattended and it will stop by itself. Of course, you need to save the script with a name you can remember so you can reuse it.