Methods and apparatus to determine audience viewing of recorded programs are disclosed. An example method disclosed herein comprises processing first bus information obtained by monitoring a bus of a time shifting device to determine a record time corresponding to when the time-shifting device stored data associated with first media content being recorded for later presentation, processing second bus information obtained by monitoring the bus of the time shifting device to determine a playback time corresponding to when the time-shifting device later retrieved the data to present the recorded first media content, and estimating a possible distribution time corresponding to when the first media content was initially distributed to the time-shifting device based on a difference between the playback time and the record time.