You need set chmod for thatmake your file executable.
chmod +x /mnt/local/ext001/MEDIA/NZBGet/scripts/videosort/VideoSort.py
or
chmod 555 /mnt/local/ext001/MEDIA/NZBGet/scripts/videosort/VideoSort.py
then, you can run that:
./mnt/local/ext001/MEDIA/NZBGet/scripts/videosort/VideoSort.py.