Original sentence: On June 18, 2007, Blockbuster, Inc, the largest chain of video game and DVD rental shops in the world, announced that its next batch of high definition DVDs will be exclusively offered in the Blu-ray format
Edited sentence: On June 18, 2007, Blockbuster, Inc, the largest chain of video game and DVD rental shops in the world, announced that its next batch of high definition DVDs will be exclusively offered in the Blu-ray format which is causing wide speculation that HD DVD has been dealt a potentially fatal set-back