Many users plug in a camera and "port forward" it through their router so they can see it from work, but they never set a password. UPnP (Universal Plug and Play):
If you own an IP camera, here is a step-by-step guide to ensure that your views.html (or similar) is never indexed by a search engine. inurl viewshtml cameras
Based on historical Shodan and Censys data combined with Google dork results: Many users plug in a camera and "port