This seems pretty straightforward but it took about half an hour to figure out reading through documentation and mistral chat. I tried a bunch of formats but audio wasn’t working. After some time I landed at this, it also let’s you save private membership videos with browser cookies.

yt-dlp -f "bestvideo[height<=1080]+bestaudio" --merge-output-format mp4\?list\=PL6W8uoQQ2c61X_9e6Net0WdYZidm7zooW --cookies-from-browser brave:Default