Using the Record Video function, game audio is also recorded (many props to those in the engineering team that made this possible, by the way). However, it defaults to 64kbps, which is pretty low quality. Now, video bitrate can be changed from its 5Mbps default using an ADB property, say to 20Mbps:
@NinjaGG Any response from the team re: settings for the audio bitrate? Would also like to know if I can change from the default mono to stereo recording.
S7 Exynos Nougat. 2017 Gear VR. Public test channel.