I've only watched the first 5 pieces, and I know this stuff pretty well. But I think the part where Jeff shows a true non demosaiced image, talks about Raw linear capture is real worthwhile.
What I found interesting and disconcerting was Jeff's continuing to regard a raw file as gray scale and an RGB TIFF as color despite our previous discussion on the Adobe Camera Raw forum. Strictly speaking no file contains color, since color is a perception that occurs in the brain. What files contain is information necessary to create a tristimulus response that is perceived as color when the information is projected on the retina and decoded in the central nervous system.
An RGB TIFF image could be viewed as three gray scale files, but it is more since each layer contains information about the color of each pixel; when the file is viewed with a color aware application, the viewer perceives color. Similarly, a raw file contains color information about each pixel that is overlain with a color filter. In the raw file, all the information is on one layer in the form of a mosaic, whereas it is present in three layers in the TIFF. Each pixel records only luminance, but since the color represented by the luminance is known, color can be generated.
Jeff believes that color is generated when the file is demosaiced and the missing colors in the mosaic are filled in by interpolation and he proceeds to prove his point by viewing the raw file in a non color aware application (dng_validate). However, if you view the file in a color aware application, the colors are there as shown in this screen shot from Rawanalyze. In the shown view, Rawanalyze takes each pixel of the raw file and displays it on screen in its proper color but there is no demosaicing, white balance, interpolation, or gamma curve. The image is greenish because there are twice as many green pixels as blue or red pixels and no white balance has been applied.
If you zoom in, you can see the mosaic pattern and the color of each pixel. There there is relatively little blue in the image and most blue pixels appear as black, but some blue is present towards the center of the image.
In conclusion, a raw file is no more gray scale than an RGB TIFF.