NEW YORK—In a cease-and-desist letter sent to Google's attorneys last week, media conglomerate Viacom demanded that YouTube immediately pull 400,000 ex-TV viewers from its industry-leading video-sharing site. "These viewers clearly belong to Viacom and its related entertainment subsidiaries," stated the letter, which called the co-opted viewership "the result of an investment of  hundreds of millions of dollars by our company." "Should YouTube fail to adequately address this blatant infringement, Viacom will not hesitate to assert its ownership rights to its intellectual property." The letter threatened further legal action if all the 400,000 viewers in question are not removed from their desks and returned to their couches by the end of the week.