How to set up USB camera for Octoprint on Debian system
You need to install a web-cam server on your Nettop. Octorint recommends Yawcam for windows and mjpg-streamer for linux.

mjpg-streamer: https://github.com/jacksonliam/mjpg-streamer
Yawcam: http://www.yawcam.com/

OctoPrint has instructions for installing mjpg-streamer on a raspberry pi. The process should be very similar for a Nettop running Debian so its a good starting place. The instructions are a little ways down the page: https://github.com/foosel/OctoPrint/wiki/Setup-on-a-Raspberry-Pi-running-Raspbian