VLC + Macbook Pro + RX-V473

[i-make-robots]

Hi!

I have a Yamaha RX-V473 receiver that takes HDMI and Airplay. I can't get sound and video playing at once.
Please: Is there some magic combination to get both at once?

On my 2011 17" Macbook Pro I have a LOGIX firewire to HDMI adapter going to HDMI 1 input on the receiver, which connects to the speakers and the TV.
On the Pro I'm running VLC with a movie playing. I can get video on HDMI 1 just fine, but no sound.
In VLC I change the audio output to "airplay". Video on the TV disappears to be replaced with "airplay now playing". I can hear the movie but I can't see the movie.
If I switch to HDMI 2 and then back to HDMI 1 I get the video back and lose the sound.

I also tried an audio cable from the headphone jack on the pro to the various audio inputs (white & red) on the back of the receiver. Same thing - one or the other, not both.