Coming from years of running Media Pro through multiple iterations (and still nursing that database along) - this feature is implemented by way of watched folders. Essentially the user right clicks for context sensitive options on single folders, one of which is to Auto-Update the folder. If there are changes to that folder the database is updated as a background process based upon user selected frequency - every 1 minutes, every 5 minutes, never. Media Pro recognizes the "new" item - file, folder, subfolder but processes it in the background. This keeps the user from needing to manually activate an update to the catalog for a watched folder(s). While it is likely CPU intensive, it does keep me up to date in a catalog without intervention.
