I Also downloaded Deadpool, it would not start.
Then I went into the audio, subtitles menu....I had "Prefer AC3 Passthrough" checked....as soon as I unchecked it, the movie started playing with 5.1 audio......something I can not do on Netflix..(Silverlight, HTML5 will not pass 5.1)
But I found a hack to allow AC3 Passthrough, via HDMI. So now I can either send the encoded 5.1 to my Oppo 105d, or send the decoded 5.1, through my Dirac 8 channel software, then to the Oppo via HDMI.
I do not use the Optical out, it's not even connected.
Ever since, I've had no problem playing any movie I've rented or bought.
But iTunes will not send 7.1 to the Mac mini, although according to Apple, such streams can be had via 🍎TV 4 or a new iPad.