Video decoding on NVIDIA GPU's without iGPU's on High Sierra?

Managed to install Mac OS High Sierra(17G8037), on my GTX 1080Ti/Ryzen 1600X system. NVIDIA webdrivers(387.10.10.10.40.131) seem to be working well, but I can't figure out how to enable hardware accelerated video decode.

This mentions that the kext should do it automatically. I have tried various "shikigva" values, but none of them seem to do anything :(

Loaded kexts

AppleMCEReporterDisabler.kext
Lilu.kext
WhateverGreen.kext
AtherosE2200Ethernet.kext
NullCPUPowerManagement.kext
FakeSMC.kext
RealtekRTL8111.kext
AppleALC.kext
IntelMausiEthernet.kext
SmallTreeIntel82576.kext