Streaming AUDIO ONLY on App (SUGESTION)

As others have stated, there is no way to record your audio while using the 'record from now' function.

I stream to mixer and that captures my mics audio, and it's really easy to do too.

The only other alternatives to a capture card is to stream directly from your console to Mixer or Twitch, or use the Xbox App on Windows 10 to stream your console's audio and video to the windows 10 device, then you can use some other software to record,
or stream. ( I hope that made sense).

Bistream is undecoded audio. It means the console can take an audio stream from a source (like a Blu-ray) and send that audio out the HDMI and optical ports. Normally, bistreaming means that any audio from the player software or the system is no longer available
because the audio stream is just whatever was encoded on the disc. It can't be mixed with app or console sounds.

SOLVED: I had to turn on Media streaming in "Media streaming options", a buried control panel screen that the only way I know how to find is by going to the start screen (win 8) or start menu (win 7) and typing "media sh". I also installed the Xbox Video
app on the Xbox. Without it installed, video files were playing audio-only in the Xbox Music app.

These are on the fly compressions of gameplay audio, not passing the audio from a disk or stream. Obviously it only needs one or the other

It's slightly irritating, but if you don't want to download the library to a PC and stream it that way, I have my chromecast connected to the HDMI in of the xbox to stream content to my TV without having to change the channel, that will allow you to stream
from the Google Music app on any other device, it will mix the game audio and tv audio. But it works.