Google-owned YouTube won a major victory Wednesday when a federal judge ruled the video-sharing site was protected under U.S. copyright law. Viacom, which vowed an appeal, was seeking $1 billion in damages in a case testing the depths of copyright-infringement protection under the Digital Millennium Copyright Act of 1998. The ruling, if it survives, is a boon for internet freedom, especially as it applies to search engines, video-hosting companies, picture-hosting services like Flickr, social-networking sites like Facebook and micro-blogging services such as Twitter. But it will make it all the more difficult for rights holders to protect their works. In short, Wednesday’s decision ...