Add 'YouTube' Codecs VP8 and VP9

[pvdl]

The YouTube plugin can't play streams correctly when you use it in Full HD or in 4K.
Video with no sound, or black screen.
I think it is related to the missing codec VP8 or VP9.

It was removed in the code, but can it be added again?

Used: Mutant HD60.

[WanWizard]

The HD60 uses a HiSilicon chipset, and doesn't use gstreamer. It uses a custom ffmpeg provided by the manufacturer, nothing much we can do about that.

[eriksl]

Besides that, these codecs may or may not be implemented in hardware in the SoC itself, we can't know that. The manufacturer remains the one to address anyway.