HONG KONG -- Movie pirates are going after Blu-ray, using a technological twist that makes their illicit copies both cheap to make and tough for consumers to spot.

Pirates are taking advantage of the fact that many viewers can't tell the difference between Hollywood's new high-definition, higher-priced Blu-ray movie format and a bootleg format -- called AVCHD -- that's a grade lower: AVCHD uses 720 horizontal lines of resolution instead of Blu-ray's 1,080, but still offers a sharper picture than an ordinary DVD on high-definition...