I'm not sure about the sounds of those guns though, I believe they used different sounds.
Or did the 37mm's really sound like that? (and I believe WWII guncams didn't have any audio)
The very last one you see the entire area peppered with shrapnel hits, as he definitely hit the target.
I believe that's the Junker's machine guns, you can hear it on the film.
Pilots would often use their (small calibre) machine guns to aim, when they hit the target with MG, they'll fire the BIG ones

EDIT: Dang! That's some high water splashes coming from those rounds!