From the manual:
REPLAY TRANSMISSIONS
Your scanner Replay feature acts as an instant replay of the transmissions you’ve just heard. You can set how long a period Replay records for instant playback. This period can range from 30 seconds to 240 seconds (4 minutes). While you can replay that recording immediately and continue replaying it, you cannot save it for future listening.
RECORD TRANSMISSIONS
With your scanner, you can record transmissions. When you begin recording, your scanner adds the Replay recording buffer to the recording. These recording sessions are saved and can be replayed on demand. Rename and delete sessions through the Review Recordings submenu.
Replay the Last Transmissions
While scanning, press Replay. Turn the Scroll Control to select recordings.
Press Channel to pause/resume replay. Press Replay to exit.
Note: Replay is not available when recording is enabled.
While they seem similar, Replay and Record appear to be two different creatures. Replay is an on-going process recording transmissions the scanner hears for the duration you set. Recording is where the scanner records all of the transmissions it hears until you cease the recording function.
Since you are already capturing the transmissions during any Recording process, I can see where the Replay function is not necessary.
I think and if I'm wrong, I'd appreciate clarification, that the "stuff" from a Recording Session goes in the "User_rec" file on the scanner memory card and the "stuff" related to Replay is in the "inner_rec" file folder.