Alright, I know this is a real long shot but, does anyone ever remember seeing this image in a U-Boat documentary? I found this pic on Uboat.net of U-371. Someone was trying to identify the insignia. It is the insignia of Waldemar Mehl on U-371. It's one of only two images that can be positively identified as U-371, the other being a nice image of the insignia on the front of the tower prior to the Turm IV retrofit.
But I digress, I've been looking everywhere for this video clip (the original post on Uboat.net was in 2011 and the youtube link is dead). The main reason is, in the interrogation report, in the description of the flak weapons, the report contradicts itself. In the initial description of the boat it lists the Platform 2 gun as a single 37mm but in the report of the sinking, it is reported as a quad 20mm. If I can find that video clip, I can determine with certainty which flak gun it had.