Comedians Jon Stewart and Stephen Colbert, whose programs were once among the most viewed on YouTube, were requested by the video site to give testimony in legal proceedings as it fights a $1 billion lawsuit by Viacom Inc, according to court filings.

The two hosts of the Viacom hits The Daily Show and The Colbert Report were listed as numbers three and four out of 32 people called by YouTube to give a deposition in Viacom's case against it and parent Google Inc, according to a document filed in the U.S. District Court for the Southern District of New York last week.

Viacom Executive Chairman Sumner Redstone is number 8 on YouTube's list. Viacom Chief Executive Philippe Dauman and general counsel Michael Fricklas top the list.

At the head of Viacom's list are Google founders Larry Page and Sergey Brin and Chief Executive Eric Schmidt.

Viacom sued Google and YouTube in March after failing to reach a distribution agreement. Viacom said YouTube carried the entertainment company's programs on its site without permission.

Since then, hundreds of thousands of Viacom clips, many of which feature the two comedians, have been removed from the Web's top online video service.

At the time, Viacom said its Comedy Central shows were among the most viewed video clips on YouTube's service overall, which allows users to upload material. Ahead of the suit, Colbert had even urged fans to make him a star on sites like YouTube.

Google has said it abides by existing laws that protect Internet services from the content uploaded by users, so long as it promptly takes down copyrighted materials that were placed there without permission after being notified.

(Reporting by Kenneth Li)

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