Hey guys, first post here and thought I would share a solution I've found to playing Netflix Dolby Digital 5.1 on the beam.
I have used an NVIDIA Shield and an old Sony Tv with HDMI ARC (also worked with optical) along with a Beam and 2 Play ones.
Apparently it works with Amazon Video and DTS 5.1 audio as well. I have only used it with Netflix so that's the only one I can verify for now.
Here's the link to the instructions on how to do this.