One of two of Grass Valley’s Blockbuster video rental stores is closing this week with a liquidation sale ­ongoing at the Brunswick location. A sign on the store’s doors indicated the store’s imminent closure, but an employee reached by phone was unable to determine the duration of the liquidation sale. The store’s manager did not return a phone call Monday. As technology has made the rental of movies and television shows increasingly digital in format not necessitating a physical disc, Blockbuster has struggled in recent years. The company has shuttered stores nationwide in an attempt to cut costs. Check back …