Most people see the explosions, bodies, and training camps on the nightly news, and they think, "wow, that's terrible." or "Why would these terrorists want their training footage out to the public?" The simple answer, recruitment.
Think of it this manner, the Blue Angels are employed by U.S. Navy as a recruitment tool and a means of publicity. The terrorists are doing the same thing, when "wanna-be" terrorists are contemplating joining, seeing large, organized sections a terrorist organization could give them that last little push they need to sign up.
Q. Do you think with, this being the case, the nightly news should be more careful about what they show on tv? describe