Well, I'm mostly up and rolling. Haven't had a whole lot of time to "play" yet because of needing sleep. Tested a couple 1080p movies and they worked flawlessly but only ran for a handful of seconds. Watched a 720p TV show and went to sleep.
I actually wasn't able to get sound working on the nightly builds, couldn't find a combination that worked in the audio setup.
My audio.conf looked like this, which I had to add, it was not present in Configfiles:
pcm.!default hdmi:NVidia
pcm:iec958 hdmi:NVidia
And then my setup in the System->Audio Output settings were of this nature:
Audio output = hdmi
Speaker configuration = 2.0
boost volume: check
ac3: none
dts: none
Audio output device = hda nvidia hdmi
Passthrough output device = hda nvidia hdmi
I just have it plugged directly into a TV right now. If you are plugging it into an AV Receiver, adjust the "upper" settings as needed, ex. 2.0/5.1/7.1 and then AC3/DTS.
The tricky part was getting an Audio output device and Passthrough output device that worked. These 2 options were not available in the nightly builds and I tried painstaking "guessing" combinations for them in the current nightly to no avail. I do know I had AC3/DTS enabled at first and I wouldn't get any errors or sound on my DTS streams. Had to disable it so it downmuxed it for my device.