Each method has is pros and cons. WiFi can drop out and it's painfully slow for 4GB HD video files. Constantly removing and inserting SD cards does them no favours. And dragging and dropping is hard to automate with a script.
Finding the GoPro on the command line takes effort. I personally couldn't do it. Yet Nautilus finds the camera without any problem. And if you look at the actual address of the camera in Nautilus (ctrl+l). Things get a bit stranger still. It's not a normal directory listing. Instead we get something weird , "gphoto2://[usb:003,003]/". Which the usual command line tools won't touch.
There are a number of ways we can get around this problem. We can opt for WiFi and wget. Except WiFi is slow. Fortunately the clue we need is in the camera address. In particular the "gphoto2" part. This seems to be part of a suit of tools for nix OS's. It allows them to talk to digital cameras. And Ubuntu doesn't have the command line tools installed by default.
We can however fix this. Open a terminal and run the following command.
sudo apt-get install -y gphoto2
Before attempting to use the gphoto2 command line tool. Unmount the GoPro in Nautilus. Otherwise the gphoto2 command line tool won't be able to talk to the GoPro.
I haven't actually downloaded any files with this tool yet. But I can confirm that it will talk to a GoPro Hero 4 Silver edition camera. There are a lot of switches listed in the man page I'd like to read over and understand before diving in. But if you want to download files from your GoPro via the command line over USB. This seems to be the way to go.
To be continued ...