Al-Qaida posted a 56-second video Friday of rockets being fired at what it claimed was a US military base in Afghanistan. The tape appeared to be the latest in a series of videos that the terror network has released to convey that its insurgents are faring well in the Afghan war. The base was not visible in the video, which showed several rockets being launched from a forested hillside in the Balwara area of Afghanistan in November, according to a subtitle. The video, which opened with old footage of US vehicles exploding as they were hit, surfaced on an Internet site where al-Qaida and other militant groups are known to post messages. Its authenticity could not be independently confirmed. The pictures were accompanied by a song whose lyrics included the line: "Burn the Christians, fight the devious Christians who worship crosses."