Just in case someone else is using the Silence Picture YUV422 feature of ML with Mac OS X:
I haven't found a slim and quick tool for Mac OS X to convert the .422 file format into a more common format, so I took the great groundwork by Wolfgang Hofer [hof@gimp.org] and used it as basis for a small terminal / command line tool to convert the .422 files to TGA files. I would have preferred PNG as output format, but that would have taken significantly more development time and TGA files are fine for Quicktime image import as well for creating time lapse movies with this ML feature.
You may download this tool compiled for Mac OS X including the source code (which should compile on other platforms with a few changes as well) for free at:
http://badtidude.com/dnlds/fdl.php?dnldf=MLRaw422ToTGA_MacOSX_release_2013_12_20.zipTo use it on Mac OS X, open a terminal window, drag and drop the executable file from the unpacked zip into the window, then drag and drop one ore more .422 files to the terminal window or even better the folder which contains the .422 files and hit ENTER.
Shortly after you should have a subdirectory named ML422YUVconverted containing the converted .tga files which you may import into Quicktime 7 Pro.
Please note that this tool is provided 'as is' as I've got loads of other things on my plate

.