video format for pre-demosaic'ed stream
Turns out the answer is yes. Such format is called CinemaDNG and is used for professional video production since 2009.

Here's the spec for the format: http://download.macromedia.com/pub/labs/cinemadng/cinemadng_p1_spec_091009.pdf

Among other things it supports:


Integer sensor values of any bit depth from 8 to 32 bits
Arbitrary size color filter arrays with up to seven color channels
Black level, white level, and linearization parameters for scaling of sensor values
Color-processing parameters for mapping camera RGB to CIE XYZ color space


Adobe's Creative Suite supports CinemaDNG on both Windows and Mac OS platforms since version 4 and the codec (at least for Windows) is available from Adobe's website: http://supportdownloads.adobe.com/product.jsp?product=194&amp;platform=Windows

There are other products out there that process video in CinemaDNG format, some even with GPU (CUDA) support.