Do you use a flourescent light? It looks as if an aritficial light is interfering. This fenomenon is also called banding or flickering. You can try to adjust some camera settings. I attach a capture of a camera configuration dialog, it might differs from yours but, more or less, should include similar settings.

Open the camera configuration dialog (Configuration -> Options > General options -> Settings button) and try the following (test if each step solves the problem before going to the next):

  • Adjust the "anti-flickering" option (also called Power Line Frequency) to 50Hz
  • Set the exposure in "Manual mode" (or disable auto-exposure or the like), then manually adjust the exposure slider until the flickering disappers and you get between 25 and 30 fps.
  • Disable other automatic controls (e.g. auto white balance)

Hope it helps