mwindow->preferences->set_file_probe_armed("FFMPEG_Early", ffmpeg_early_probe);
mwindow->preferences->set_file_probe_armed("FFMPEG_Late", !ffmpeg_early_probe);
mwindow->preferences->set_file_probe_armed("FFMPEG_Early", ffmpeg_early_probe);
mwindow->preferences->set_file_probe_armed("FFMPEG_Late", !ffmpeg_early_probe);