yi.org Dynamic DNS does not actually host the webpages it assigns names to; the majority of them are served off of individual computers. The only people who can do anything about piracy or other content-related issues are the individual hosting the content and their Internet Service Provider.
To look up the email address of the individual who owns a hostname, you can use yi.org's hostname search. Enter the name of the host you wish to look up here:
Here are some directions to help you contact the Internet Service Provider:
There is a public webpage operated by the American Registry of Internet Numbers to do this at http://www.arin.net/whois/, and many operating systems have a built-in "whois" command. The results from the WHOIS will supply you with a contact email address to complain about content-related abuse issues.
Send an email to abuse@yi.org.