Sorry I have not responded immediately - I have not got the email notification somehow.
If the help screen of dfu-programmer is shown to you after issuing launch then you might have old dfu-programmer version.
This command has been renamed in 0.7 version, while in 0.6 it was called start. This should be added to the guide (@nitroalex).
I wonder why the device is not visible to you, even with sudo. The update process is usually straightforward on Ubuntu. If you would find yourself once again in this situation please attach results of lsusb command as well.
Lesson learned from this is making own update application, which would collect system details and suggest possible solutions to the connection issue.
Just for completeness (for others reading this topic) - linking your working update guide for Windows 10: