LAGOS, Nigeria ? Looking sad and frightened, dozens of barefoot girls sat huddled together wearing gray Muslim veils as they chanted Quranic verses in Arabic. Some Christians among them said they had converted to Islam. In the video released Monday, the Boko Haram terrorist network offered the first public glimpse of what it claimed were some of the nearly 300 girls kidnapped from a Nigerian school a month ago ? and issued an ominous threat. The girls will not be seen again, the group's leader said menacingly, until the government frees his imprisoned fighters. I swear to almighty Allah, you will not see them again until you release our brothers that you have captured, Abubakar Shekau...