This is what led me to believe the behavior I described earlier. From page 8 of the 970 user's manual:
"IR output Feeds an infrared flasher attached to another piece of audio/video gear. Any infrared remote signal received by the Model 970’s front-panel sensor or by an external sensor connected to the Model 970 will be relayed through this jack, so concealed audio/video devices can be controlled by remote."

Like I said, I am very curious now...