Dear Alex_HTC
Thank you for your answer Posted on January 21.
As my experience, watching youtube using VIVE Flow is very hard work. so, I tryed install android apps.
It takes a long time to find screen capture on VIVE FLOW by myself.
Finally, I attached screen shot of VIVE FLOW.
There are just 2 option as like "Installed" and "Not Installed" on VIVE FLOW screen.
I downloaded apk file from https://en.uptodown.com/developer/google-llc, one by one.
1. By ADB Command.
I had try 3rd party apk files using by VIVEFLOW_Windows adb command
as like "adb install -r youtube-vr-1-28-63.apk" step by step.
but there's no app on "Not installed" option.
2. Using Download files on VR.
a. copy all files to Download of VIVE FLOW, and then on Flow, I had try install one by one.
But, Same as there's no app on "Not installed" option.