I can start and stop a recording in QuickTime Player 10.5 using JXA, but I'm having a problem exporting.
qt = Application("QuickTime Player")
movie = qt.newMovieRecording()
qt.start(movie)
delay(3)
qt.stop(movie)
qt.export(movie, {in:Path("/Users/User_Name/test.m4v"), usingSettingsPreset:"720p"})
The export statement throws an error "can't get object."