Revision3, a legitimate company that distributes HD video over the Internet using BitTorrent, was not amused, and the FBI is investigating.
Any legitimate Internet provider should refuse to provide services to companies that engage in illegal or immoral tactics to try to stop peer-to-peer piracy of copyrighted content, such as denial of service attacks or interference with services that are being used legitimately, even if they are also being used for piracy. If they don't have methods which can be targeted specifically against the copyrighted content they are authorized to protect, then their methods cross the line, in my opinion.
MediaDefender's upstream network providers are Savvis (ASN 3561), Beyond the Network (ASN 3491), WV Fiber (ASN 19151), and SingTel (ASN 7473). They all should have a problem with denial of service attacks by their customer.
MediaDefender was previously in the news in September 2007 when its security was breached by hackers and 700 MB of executive emails and the content of VoIP telephone calls from the company were leaked to the Internet. This seems to me like a company that should not be in business.