I imagine it was a clip from an old war movie and the subtitles were overlaid on the original subtitles. At a couple of points the dialogue you heard actually sounded a bit like what the subtitle said. I think it was essential to have the dialogue there because it conveyed the tone of the speaker to give life to the subtitles beyond that which the action did.

I had to pause it partway through because of the pain from laughing so hard.