Don't forget to build 'correct' ELF64 binaries for broad elf(glibc)/linux distro support (-static-libgcc -static-libstdc++, and tight glibc ABI version control with binutils VERSION scripts).
RTSP support, twitch-style in-game visio, any kind of non-game Unity apps (there are many), 360 video playback, mediaplayer in VR headset, simulators of all kinds, etc..
For a sandbox game this is very useful, where you can spawn video players in-game. For social games (like VRChat) this is also great since synced video playback is a very popular feature for people to watch content together in VR.
It uses OpenGL rendering through GLX and EGL, with DMA-BUF texture sharing to pass video frames efficiently to Unity’s renderer.
Only x86_64 is supported at this time. In the future, I will add ARM64 support as well as Vulkan.
At least those build options should be default.
For cutscene playback?