Blu-ray appears to be opening up a lead on its high-definition rival, according to first quarter sales figures gathered by Home Media Magazine. The numbers weigh heavily in Blu-ray's favor: 70 percent of all HD titles purchased by consumers were in that format. For the month of March alone, that figure was closer to 75 percent. Sales of Blu-ray discs also passed the 1 million mark since their launch. But there's a very big reason to take all of these numbers with several grains of salt; more on that later.