According to Windows task manager VP9 video decoding executed on CPU instead of GPU. It is a known fact that Radeon™ RX Vega M GH graphics
does not support VP9 HW decoding. However Intel® HD Graphics 630 has HW support for VP9. How I can get HW accelerated VP9 video playback on Intel® NUC Kit NUC8i7HVK (HADES CANYON)?
The TPS on page 19, Graphic Capabilities do not mention support for VP9 regarding the HD 630 and it also states that the graphics outputs are not physically connected to the HD 630, so I think that this will required that the video player app supports Intel Quick Sync...
I had to go to the experts to get an answer for this. They are telling me that it is true that VP9 is not supported by the dGPU; it does not have native acceleration, only hybrid decode capabilities. They are also telling me that, in order to use the capabilities of a graphics engine, this engine must be connected to the output (i.e. the data destined for an output must flow through a GPU before that GPU can process it). In the HV design, all outputs are connected to the dGPU; the iGPU is not connected to any output (it's effectively headless). This means that you cannot make use of its DRM/BD/VP9 capabilities (though it can support transcoding via QSV).