You can make only newest recordings in your available for the VMS users.

To do this, select the history (in days) in the appropriate field and click Apply. 

If the history value is set at 0, all recorded video is available for playback.

You can view only video recordings not exceeding the retention time setting. All other videos will be deleted.

Further, if you are increasing the Archive retention time (0 - stands for unlimited time), this setting is applied for new records only. Earlier records falling outside the initial retention time become inaccessible.