Well, that is sadly a bug of Apple - it mostly happens, when you run iMultiviewer on a MacBook Pro Retina. To fix that, open Terminal.app and enter the following:
defaults write com.apple.cmio CMIO_Unit_Input_ASC.DoNotUseOpenCL -bool YES
You'll find the Terminal.app in Applications/Utilities/Terminal.app
Then please restart your computer. After the restart, everything should work as you would expect.

CMIO is Apples API for third party developers (CoreMediaIO) which has actually a kind of bug when using Open CL. If you turn it off (which you actually do, when using this terminal command) the received image from the graphic card is the right one - and not the green one.

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