Faced with the daunting task of renewing a pile of major contracts, amid increasing threat from cross-platform competitors, audience measurement giant Nielsen has lashed out by filing a lawsuit seeking to block the launch of comScore’s new Extended TV service. It isn’t the first time the two rival companies have clashed, but in this instance, Nielsen has revealed some major cracks in its historically solid standing in US TV viewing data. Nielsen alleges that the audience data provided by Extended TV is based on its own Portable People Meter (PPM) data, claiming that it violates an agreement between the two. This is despite a ruling by the FTC (Federal Trade Commission) back in 2013, in which Nielsen had to license…