"Since we started this ongoing war which they call state of emergency ... In some instances soldiers who faced us turned and ran," Abubakar Shekau said in the hour-long video.
He claimed Nigerian forces "threw down their arms in flight."
He called on like-minded Islamists in countries including Afghanistan, Pakistan and Iraq to join the fight to create an Islamic state in Nigeria.
"We call to us our brethren in these countries I mentioned. Oh! Our brethren, come to us," he said in the video, which alternates between Arabic and the Hausa language spoken across northern Nigeria.
The video was delivered to AFP though an intermediary in a manner similar to previous Boko Haram messages. The images of Shekau in the video are consistent with those previously released.
The Boko Haram leader was designated a global terrorist by the United States last year.