Rental chain Blockbuster Video will close between 810 and 960 stores by the end of 2010, an SEC filing reveals. While putting a significant number of people out of work, and closing off some markets, the move is expected to add another $50 to $60 million to annual earnings before expenses like taxes and interest. The company has over 7,000 stores worldwide at present, scattered across Asia, Europe, the US and Australia.