In order to set up ESM to push the date/time settings to the cameras, you will need to set up the server (you wish assign to sync ESM with in the admin interface) as an Authoritative Time Server. Please see this knowledge base article "How to configure an authoritative time server in Windows Server": http://support.microsoft.com/kb/816042.
Attached is a .bat file that you can execute to set up your server as an authoritative time sever. It has been changed to .ba_ for you to save and execute. You will want to edit this file and change the IP address to point to the IP address of the server you will want it to sync to (May be itself).
In the Admin interface, under the devices, choose the archive location. In the NTP Host field, enter the IPAddress of the server you want to sync the cameras with. This will only sync the cameras in this location to the NTP host specified. Each archive location that is linked to the management server will need to be configured as well.
If you are configuring this after the cameras are recording, you will need to go to the archive server and restart the ipConfigure Recording Control Service to push this setting to the cameras.
Windows Time Service is default set to manual start. You should change this to automatic to avoid having to restart this service manually after reboots.