What is this strange second camera? I don't know is this is the correct place to ask this but ...

I've watched several "making of" of current movies and noticed a thing i cannot explain. 

What is this strange "secondary" camera you can see near the main camera?

Image: 


Reference:  (5:52 and 6:50)
That is a specially built enclosure called a Sound Blimp, for a still camera, which renders it completely silent, so they can shoot stills without clicks and beeps disturbing the filming.