I'm the creator of the second webcam viewer (cryptogasm.com/webcams). To answer a few questions:
1) Some of the cameras are intentionally accessible (i.e. the public ones), but a lot aren't. Those are usually security cams that people have set up in their own homes.
2) None of the cameras are being "tapped" into in the hacking sense. All the feeds can be accessed by sending a single HTTP request to a specific URL, and not passwords are needed. I don't add any cameras that would require stolen credentials to access, although there are plenty out there that qualify.
3) As to how I got the feeds, they were obtained via Google searches and various queries on Shodan (http://www.shodanhq.com/)
As a matter of principle, I remove the feeds that feature children from the viewer whenever I find them, and will happily remove feeds if people contact me. That said, all of the feeds are still accessible...you just have to find them manually.
An FAQ is here: http://cryptogasm.com/webcams/faq.php