On my sblive I have to set the recording option in the volume applet to "what you hear" to get speclab to see the dvd audio.
Also I should mention that the color scale above is a bit wrong. There is no way to get blue to cover so much of the range, so just set it so it's approximately blue at the left and purple on the right. Also if anyone posts their own shots be sure to include the color scale for reference.
Edit- I replaced the color scale image above with a correct one.