Hi yecart,
An exploit toolkit checks to see if you are running any software that contains unpatched security flaws that can be used to install malware without any user action. Java and Adobe Flash Player are most frequently targeted. This is why PC owners are always admonished to keep all software up to date on security patches. Norton recognized the attack and blocked it. It is likely that a malicious ad or user post on a legitimate site redirected your browser to adultvideoz where the attack was hosted. You can prevent these redirections from occurring in the first place by blocking JavaScript in your browser.
http://krebsonsecurity.com/2011/05/blocking-javascript-in-the-browser/