>>942
問題なくダウンロードできる

933 が書いたように一旦ログインして動画を再生していないのではないか？
あるいはコマンドラインがまちがっていないか？

たとえば下のように表示されてダウンロードされる
エラーメッセージを貼り付けてみてくれ

フォルダー\yt-dlp --cookies-from-browser chrome https://www.youtube.com/watch?v=WKY1mn7cwl8
[Cookies] Extracting cookies from chrome
[Cookies] Extracted 172 cookies from chrome
[youtube] WKY1mn7cwl8: Downloading webpage
[youtube] WKY1mn7cwl8: Downloading android player API JSON
[youtube] WKY1mn7cwl8: Downloading tv embedded player API JSON
[youtube] WKY1mn7cwl8: Downloading web embedded client config
[youtube] WKY1mn7cwl8: Downloading player 02208bb4
[youtube] WKY1mn7cwl8: Downloading web embedded player API JSON
[info] WKY1mn7cwl8: Downloading 1 format(s): 248+251
[download] Destination: Anaheim Police Bodycam Footage of Fatal Shooting of Brandon Lopez [WKY1mn7cwl8].f248.webm
[download] 100% of 49.64MiB in 00:06
[download] Destination: Anaheim Police Bodycam Footage of Fatal Shooting of Brandon Lopez [WKY1mn7cwl8].f251.webm
[download] 100% of 1.79MiB in 00:00
[Merger] Merging formats into "Anaheim Police Bodycam Footage of Fatal Shooting of Brandon Lopez [WKY1mn7cwl8].webm"
Deleting original file Anaheim Police Bodycam Footage of Fatal Shooting of Brandon Lopez [WKY1mn7cwl8].f248.webm (pass -k to keep)
Deleting original file Anaheim Police Bodycam Footage of Fatal Shooting of Brandon Lopez [WKY1mn7cwl8].f251.webm (pass -k to keep)