1. A method of tracking sentiment of an audience of a webcasted event by a sentiment analysis tracking system that includes at least one processor, the method comprising: transmitting, by a transmitter, a media content stream of the webcasted event to a plurality of computing devices for consumption by the audience; receiving, by a receiver, an electronic sentiment expression data message that includes data indicative of a first sentiment expression provided by a first member of the audience of the webcasted event to a member computing device; validating each one of a plurality of sentiment expressions, which includes the first sentiment expression, that are within a time period by validating that only one electronic sentiment input per respective client identifier is included within the time period; aggregating, by the at least one processor, the plurality of sentiment expressions provided by members of the audience of the webcasted event, the plurality of sentiment expressions including the first sentiment expression; calculating, by the at least one processor, a sentiment value for the time period based on the aggregated plurality of sentiment expressions from the members of the audience; outputting for the time period, via the sentiment analysis tracking system, the calculated sentiment value.