Click the Calendar icon within the Market Replay tool bar and select a date and time you wish to start "Market replay" from. Once the date and time are inputted click the "Jump to time" button which is located directly to the immediate right of the Calendar icon.
Once you click "Jump to time" button this will make the chart jump to the start time you set for the date of time of market replay. You will also notice top left corner of the chart it should say "Playback". You can now click the play button in the market replay toolbar, you can pause it anytime you wish, and increase or decrease speed. To go back to regular chart that is NOT market replay, you can click the "Terminate Playback, Go to Realtime" which is the button located to the immediate left of the speed slider control.