Download YouTube videos. Video formats are listed at the top of the watch page. Video links are tagged so that they can be downloaded easily.
The only three video streams with audio are 720/MP4, 360/MP4 and 360/WEBM.
The rest are either video or audio streams. That's just how YouTube works now.
If you want high-res video, you got to do the work yourself. Download the video and audio streams, then mux'ed them.
You can do this using youtube-dl, for example. It downloads directly from YouTube and muxes the streams for you.
The downloaded video has no sound
Why is the downloaded video soundless?