"We told our customers about the error when we discovered it-and updated our help center to explain the issue", a spokeswoman said. This calculation tactic inflated the average viewing times by 60-80%, the social network told an ad-buying agency at the time.
"But it didn't-it reflected the total time spent watching a video divided by only the number of "views" of a video (that is, when the video was watched for three or more seconds)".
LLE One also alleges that internal documents found that Facebook had never performed a full audit of its video metrics prior to September 2016 and that the video insights team - which was responsible for investigating and fixing errors - only had two engineers dedicated to fixing errors.
Facebook developed a "no PR" strategy to avoid drawing attention to the error, according to the court filing.More news: Bellinger hitting leadoff for Dodgers vs Brewers in Game 5
The earlier court proceedings allowed them to review around 80,000 pages of internal Facebook records, and the plaintiffs said Tuesday that they had uncovered evidence showing Facebook knew about the miscalculated metrics all the way back in January 2015.
The claims that Facebook failed to act when it discovered the video metric error were in an August filing, but were heavily redacted at the time.
The complaint builds on the lawsuit they filed in late 2016 in California federal court alleging Facebook engaged in unfair business conduct when it released false metrics that overestimated the amount of time spent watching video ads, in some cases inflating viewing time by 900 percent.
"The lawsuit is without merit and we've filed a motion to dismiss these claims of fraud", a Facebook spokesperson said in a statement. The lawsuit includes fraud claims against Facebook and requests punitive damages.More news: Trump threatens to send military against immigrant 'onslaught'
In the filing, brought before the USA district court in Oakland the claimants write: "If Facebook had immediately corrected its miscalculation in a straightforward manner, advertisers would have seen a sudden and precipitous drop in their viewership metrics".
Facebook is accused of trying to hide inflated advertising metrics.
Last month, Kansas City psychotherapist Danielle Singer filed a class action lawsuit against Facebook, alleging the company had falsely inflated the potential reach of its advertisements.
Meanwhile, Facebook told the Wall Street Journal that it was "false" to suggest that the social network tried to hide the issue from advertisers. Among other sources, the suit drew on a report by industry group Video Advertising Bureau showing that Facebook's audience reach estimates in every U.S. state were higher than the states' actual populations according to the USA census.More news: U.S. may lift Turkey sanctions after USA pastor's release: Pompeo