There are actually three common kinds of bicolor LED's:
- 2 pins, with the leds internally connected in anti-parallel
- 3 pins, common anode pin, separate cathode pins
- 3 pins, common cathode pin, separate anode pins
Connecting a 2 pin bicolor LED to ground and GPIO will work, but will only give access to a single color. The approach discussed on dangerous prototypes should be fine, the disadvantage is that it consumes current when dark, that's probably ok for a small number of indicator LEDs.
I'd recommend against this approach:
as I don't think it would work, and if it does, it 'd cause degradation of the audio quality. The "CM" 1.65V is a voltage reference output that has a critical function in the audio AD and DA conversion, it is not designed to deliver current.