When using streamed MPEG based video, either for live monitor streams or events, ZoneMinder can send the streams in two ways. If this option is selected then the timestamp for each frame, taken from it's capture time, is included in the stream. This means that where the frame rate varies, for instance around an alarm, the stream will still maintain it's 'real' timing. If this option is not selected then an approximate frame rate is calculated and that is used to schedule frames instead. This option should be selected unless you encounter problems with your preferred streaming method.