The Norwegian hacker who cracked the encryption mechanism used by DVDs has turned his attention to Google's new Video Viewer.

Video Viewer, released Monday, is a modified version of the open source VLC (VideoLAN Client) software that can only play videos hosted on Google's servers. In a Web log posting, published Tuesday, Jon Lech Johansen released a patch that circumvents this restriction.

When it was launched in January, Google Video returned excerpts of close-captioning transcripts of television programs, still images from broadcasts and other programming information. It didn't return actual video clips that users could play back.

Google began allowing users to upload video to its Web site last April, and with the release of the Video Player it has developed a way to let users view videos on the site.

Google warns of security risk

Google is not encouraging anyone to download the patch, according to Nathan Tyler, a Google spokesman. "We strongly advise users not to download this modification," he said. "It could result in security vulnerabilities in their computer and may disrupt their computer's ability to access Google video."

"We've designed our player to work well for our service," Tyler said. "Once the player has been modified we can't guarantee whether it will work well with our service."

Johansen, also known as "DVD Jon," is a celebrity in the Linux community because his DVD de-encryption software let Linux users run DVDs on their PCs. The software also cracked the CSS (Content Scrambling System) copy protection mechanism used by DVDs, and in 2002 Johansen was charged with violating Norwegian law.

Johansen was ultimately acquitted of the charges a year later after a Norwegian court found no evidence that Johansen, who was 15 at the time he wrote the software, had used his code to produce or watch illegal copies of DVDs.