I watched the video before reading the thread and I was going to say that there were a lot of Italian troops and equipment in that clip so it wouldn't surprise me if the weapon was Italian rather than German. The 2 soldiers using it certainly look to be wearing Italian helmets to me, though I'm not really an expert.
Over half of the forces under Rommel on November 1942 were Italian. About 300 of his total of 500 tanks were Italian.
Montgomery disposed of about 1,400 tanks though and roughly double the numbers of men and guns. Not to mention complete air superiority.
I expect the film of an allied soldier surrendering was either faked or, if genuine, relates to an earlier campaign. The Axis weren't capturing any allied positions in November 1942. The Italians definitely made propaganda films using fake surrendering allied soldiers on other occasions.
Andy.