Webcams and Nanos. Cabling and interference advice sought
It would appear to be better if you use USB hubs every 5 meters, to a maximum of 25 meters.  That link goes to a question with answers on the SuperUser StackExchange.  The answers go into some detail about why.

There should be no interference between the cables, and if it works at all then the video quality shouldn't depend on the length of the connection.

My concern would be if the USB ports on the Nano can keep up with the data - whether you can stream video simultaneously from 4 cameras and store or process it all.



As a practical thing, I have used USB extensions to connect a webcam over more than 5 meters.  It wasn't 10 meters, but it was more than 5 meters and worked well enough.