Viacom sues Google, which acquired YouTube in 2006, acts as a willing accomplice to online users who upload clips of Viacom's copyrighted television programs on the video-sharing website, according to the AFP article posted on Google.

"We are disappointed the court granted Viacom's overreaching demand for viewing history," Google senior litigation counsel Catherine Lacavera said to AFP in an email Thursday.

Brushing aside privacy concerns on Tuesday, Stanton said that Viacom would need more than pseudonyms and IP numbers to identify individual YouTube users.

Meanwhile, Kurt Opsahl, Electronic Frontier Foundation attorney, said the court's ruling is a significant reversal to privacy rights, AFP reported.

"The court's erroneous ruling is a set-back to privacy rights and will allow Viacom to see what you are watching on YouTube. We urge Viacom to back off this overbroad request and Google to take all steps necessary to challenge this order and protect the rights of its users," Opsahl added.

Viacom made an announcement Thursday stating the data will only be used to bolster its case against Google, not to expose or pursue viewers of copyrighted videos, AFP reported.