He's saying that you could use a periodic-submission order system. Say that the period is (for ease of discussion), 1 hour, ending on the hour. All orders made during the hour are queued up and simultaneously executed at the start of the next hour. If there are too few bids/offers to satisfy all trades, then trades are satisfied using some fixed rubric (i.e., pro rata, max/min price buyer/seller will accept, etc.) Until execution, the orders remain secret (not published to the orderbook). In theory, this allows people to place orders based on a known price.
In practice, in the past (before electronic trading took over), the published orderbook was updated manually as traders submitted bids, offers, and executed sales information to the exchange.