Hackers who sympathize with radical Islamic groups increasingly are using hijacked accounts at online file-upload and distribution services to disseminate large files, such as videos of attacks on Western forces in the Middle East, new research suggests. Services like RapidShare, Ziddu, and MegaUpload allow users to share large files, yet each places certain restrictions on non-paying users, such as limiting the number, speed, and size of files that free users can upload and download. But according to analysts at iDefense, a security intelligence firm owned by Verisign, hackers from various online jihadists forums have in recent months begun posting lengthy...