In previous images, a strange error was found, so I updated the images to version 20181014.
Checked on MVR9, everything works. Added additional image with Ubuntu Bionic and built-in MPV with HW support. The video plays in full screen. For those who need to play full screen video from Youtube, I recommend To install SMPlayer and Smtube packages, configure Smplayer (in additional options to use MPV with options "--vo=gpu --gpu-context=drm --hwdec=rkmpp" ) and you will get Youtube video in full screen in Smtube.