Los Angeles - The FBI is reportedly investigating MediaDefender, an anti-piracy firm often hired by record labels and movie studios, after the company allegedly initiated a denial of service attack last weekend against Revision3, a legitimate online TV network. In a blog post, Revision3 CEO Jim Louderback recounted the events, noting that the attack focused on the server the company uses to seed content on the BitTorrent file-sharing network -- which also happens to be used for illegal file-sharing.