the file mentioned in the link you had given has a filed called camera.tegra3.so
i just copied the file and rebooted the device which did not seem to make any difference.
but when i checked pine64, it has a file called camera.tulip.so and not camera.tegra3.so
I also noticed that android 6 actually sets the UVC camera as the secondary camera device. So, when i selected the secondary camera in hangout, suddenly the video came alive. That pretty much was what i needed. But then again, ran into another problem. My UVC camera has a microphone which didn't seem to be used. So, my google hangout was without voice. Is there any setting to enable the microphone in the camera device?