This might sound complicated, but youtube videos come in many shapes, many of them have either video only, or audio only !
the best way to get a full resolution video is to download then combine video and audio !
But before we go there, youtube throttles the speed you download videos at ! so youtube-dl needs patching, an alternative would be yt-dlp (See here)
The easier way to install would be
apt install yt-dlp
Now, if you insist on pip, you can do the following
apt install python3-pip
python3 -m pip install --force-reinstall https://github.com/yt-dlp/yt-dlp/archive/master.tar.gz
Now, let us try downloading a video/audio
youtube-dl -F https://www.youtube.com/watch?v=mUvrLxaSolc
The line above will show you a bunch of options and their IDs, what you need to do now is to download the ones you need with a command such as
youtube-dl -f 270 https://www.youtube.com/watch?v=mUvrLxaSolc
Now, to combine them (Audio and video) without re-encoding…
ffmpeg -i ao.webm -i vo.webm -c:v copy -c:a copy output.webm
But remember when you download,
Only VP8 or VP9 or AV1 video and Vorbis or Opus audio and WebVTT subtitles are supported for WebM.