Abstract: A method of dynamically pacing the presentation of pre-recorded supplementary content to synchronize to live content at a live event, comprising providing the pre-recorded supplementary content associated with the event to end-user devices, with an ordered sequence of content items, each timed to be played on the end-user devices sequentially according to a predefined presentation time duration, and each associated with a scripted property, receiving real-time sensor data from sensors in a facility measuring a property of the live event, matching the measured property of the live event with a corresponding scripted property to identify a live progress of the event indicated by a progress indicator, and sending the indicator to the end-user devices to synchronize the timing of the measured properties of the live event with the timing of the content item associated with the matching scripted property.