Thanks for writing into the show! Remember that there are 5 different DVI connectors that possible. These DVI technologies are designed to propagate the signal farther away and provide a better quality of signal than straight analog signals. The 5 connectors are:
DVI-I (single link)
DVI-i (dual link)
DVI-d (single link)
DVI-d (dual link)
DVI-A (analog only)
The DVI-i types are designed for a a digital source to output to a digital or analog display.
The DVI-d types are designed for a digital source to output to a digital display
The DVI-A designed for an analog source to output to analog display.
The dual link are to support higher resolutions than 1920 X 1080 and 16:9, 16:10 aspect ratios, as long as the cables (dual link) and the devices will also support it. The single links support higher quality of signal and faster but not the above mentioned. The strange one is the DVI-A, which is designed to support a higher quality analog signal that can travel farther than the standard analog (VGA).
You're correct in the noting that pins you're referring to in the diagram are analog if using the DVI-i or the DVi-A. The 4 pins are for analog with the blade pin being the ground lead connection for analog.