The minute-long footage showed a stocky man with graying hair, standing in a rugged mountainous area surrounded by several masked Taliban fighters, some of them carrying automatic rifles and RPG launchers. The Taliban rifles were pointed at the hostage.
The man, wearing a thick jacket over a pair of jeans, was seen speaking into a camera, but his voice was inaudible in the aired footage and was further drowned by the voice-over of the Al-Jazeera broadcaster.
The broadcaster said the German appealed to his government and to the United States to withdraw troops from Afghanistan and to help him return to his family.
The video also showed four Afghans whom the network said were kidnapped together with the German. The four also appealed to the West to comply with Taliban demands.
Meanwhile, German media said the video included a demand for the release of 12 Taliban fighters in exchange for the German and four Afghans - as well as the withdrawal of German troops.
But Al-Jazeera spokesman Ayman Gaballah told The Associated Press that there was no mention in the video of such a specific demand for the release of 12 Taliban prisoners, only a call for compliance with Taliban demands.
According to earlier media reports in Afghanistan, the Taliban have demanded that 10 Taliban prisoners held by the Afghan government be released, along with the withdrawal of German troops from Afghanistan, in exchange for the hostages' freedom.
The pan-Arab satellite TV did not say how it obtained the video.
Two German engineers were reported kidnapped earlier this month by the Taliban. One of them, Ruediger Diedrich, 43, died while in captivity under unclear circumstances. His body has been flown back to Germany for an autopsy to determine the cause of death.
German media have identified the second man only as Rudolf B.
In Germany, foreign ministry spokesman Martin Jaeger promptly blasted the video.
"The video broadcast today with comments by the German kidnapped in Afghanistan is a deliberately launched document of intimidation," Jaeger said.
Jaeger added that experts at the ministry crisis unit dealing with the kidnapping were "carefully analyzing and evaluating the video message" and said the unit continues to pursue "intensively" its efforts to secure the hostage's release.
Last week, German Chancellor Angela Merkel stressed that Germany views its commitment in Afghanistan - where some 3,000 of its troops support the NATO military mission and its officers lead efforts to train Afghan police - as a long-term one.