Oh, forgot audio.
mpv --ytdl-raw-options=format=bestvideo[ext=webm]+bestaudio ...
You have to toy with format options to find something you want.
But looking into it I think this is the overall better solution:
mpv --ytdl-raw-options=compat-options=prefer-vp9-sort ...
You can also put that option without the -- into your mpv.conf.