well- If I an to extrapolate what he meant,(regarding a third party preventing others from viewing the site) he was referring to Denial of Service Attacks. The Basic Idea is somebody with too much time on their hands, who has control of thousands, perhaps tens of thousands of "Zombie" PCs could set all of those PCs to the task of doing something- for example, pinging the web-site, sending fake packets to it's main HTTP port- or even sending page requests to it, and then setting the return address to some other site they want to disrupt. (the return address is in the packet).
So, if the bad guy knows two sites they want to disrupt, they can direct their "army" to send page requests to Site1, and the packets can have the address of Site2. So Site1, believing it's a valid request, generates the HTML and sends it along to site2, which has absolute no idea where this response came from, but still needs to devote resources to handling it. The basic idea is the overwhelm them with so much data that legitimate users of the site time-out, thus, they are "denied service".
