Can't generate video file "Failed: Could not open..."

[bigtreacle]

On choosing a path and clicking Generate the following error is displayed, and no video file generated:

Failed: could not open <path to file>

Messages from console:
10:25:40.870 [AWT-EventQueue-0] DEBUG peregin.gpv.App$ - saving /Users/simon/Movies/Cycing/20150510 - Three Horsemen of the Apocolypse/second horseman 10:25:47.017 [AWT-EventQueue-0] DEBUG peregin.gpv.App$ - convert project 10:26:17.483 [AWT-EventQueue-0] DEBUG peregin.gpv.gui.FileChooserPanel - opening /Users/simon/Movies/Cycing/20150510 - Three Horsemen of the Apocolypse/Leith Hill 10:26:17.483 [AWT-EventQueue-0] INFO peregin.gpv.ConverterDialog - save to /Users/simon/Movies/Cycing/20150510 - Three Horsemen of the Apocolypse/Leith Hill 10:26:22.284 [AWT-EventQueue-0] INFO peregin.gpv.ConverterDialog - generate... 10:26:22.485 [ForkJoinPool-3-worker-15] ERROR com.xuggle.xuggler - URL: /Users/simon/Movies/Cycing/20150510 - Three Horsemen of the Apocolypse/Leith Hill; Error: could not find output format (../../../../../../../csrc/com/xuggle/xuggler/Container.cpp:513) 10:26:45.242 [AWT-EventQueue-0] INFO peregin.gpv.ConverterDialog - cancel or close 10:26:47.155 [AWT-EventQueue-0] DEBUG peregin.gpv.App$ - convert project 10:27:00.718 [AWT-EventQueue-0] DEBUG peregin.gpv.gui.FileChooserPanel - opening /Users/simon/Movies/Cycing/20150510 - Three Horsemen of the Apocolypse/Leith 10:27:00.718 [AWT-EventQueue-0] INFO peregin.gpv.ConverterDialog - save to /Users/simon/Movies/Cycing/20150510 - Three Horsemen of the Apocolypse/Leith 10:27:34.933 [AWT-EventQueue-0] INFO peregin.gpv.ConverterDialog - generate... 10:27:35.096 [ForkJoinPool-3-worker-15] ERROR com.xuggle.xuggler - URL: /Users/simon/Movies/Cycing/20150510 - Three Horsemen of the Apocolypse/Leith; Error: could not find output format (../../../../../../../csrc/com/xuggle/xuggler/Container.cpp:513) 10:27:42.965 [AWT-EventQueue-0] INFO peregin.gpv.ConverterDialog - cancel or close 10:27:45.321 [AWT-EventQueue-0] DEBUG peregin.gpv.App$ - convert project 10:27:58.334 [AWT-EventQueue-0] INFO peregin.gpv.ConverterDialog - generate... 10:27:58.497 [ForkJoinPool-3-worker-5] ERROR com.xuggle.xuggler - URL: /Users/simon/Movies/Cycing/20150510 - Three Horsemen of the Apocolypse/Leith; Error: could not find output format (../../../../../../../csrc/com/xuggle/xuggler/Container.cpp:513)

[Schrottie]

If you have this error, just copy another mp4-file as target, select this and then export your video.