This is a search operator used by Google to search for a specific term within the URL of a webpage. When you use "inurl:", you're telling Google to only return results that have the specified keyword in the URL.
Searching for these links is generally legal, but with them can cross into a legal gray area. Using these dorks to identify vulnerabilities is a core part of "White Hat" hacking (improving security), but accessing private feeds without permission or attempting to bypass security on these pages can violate privacy laws or computer misuse acts in many jurisdictions. How to Protect Your Own Camera inurl multi html intitle webcam free