919ですがエラーはこうなっています
yt−dlpは最新に入れ替えたんですが上手くいきません
年齢認証の無い他のつべの動画なら、問題なく落とせます
Firefoxでは再生できてるのでそこは問題ないかと

D:\yt-dlp>yt-dlp --cookies-from-browser Firefox https://www.youtube.com/watch?v=t7ykyfRmnVQ
Extracting cookies from firefox
Extracted 569 cookies from firefox
[youtube] Extracting URL: https://www.youtube.com/watch?v=t7ykyfRmnVQ
[youtube] t7ykyfRmnVQ: Downloading webpage
[youtube] t7ykyfRmnVQ: Downloading tv client config
[youtube] t7ykyfRmnVQ: Downloading tv player API JSON
[youtube] t7ykyfRmnVQ: Downloading web safari player API JSON
WARNING: [youtube] t7ykyfRmnVQ: Some tv client https formats have been skipped as they are DRM protected. Your account may have an experiment that applies DRM to all videos on the tv client. See https://github.com/yt-dlp/yt-dlp/issues/12563 for more details.
[youtube] t7ykyfRmnVQ: Downloading player 7b9b4e02-main
WARNING: [youtube] Falling back to generic n function search
player = https://www.youtube.com/s/player/7b9b4e02/player_ias.vflset/en_US/base.js
WARNING: [youtube] t7ykyfRmnVQ: nsig extraction failed: Some formats may be missing
n = Y31em5_lBbo3kBzbOd0 ; player = https://www.youtube.com/s/player/7b9b4e02/player_ias.vflset/en_US/base.js
Please report this issue on https://github.com/yt-dlp/yt-dlp/issues?q= , filling out the appropriate issue template. Confirm you are on the latest version using yt-dlp -U
WARNING: [youtube] t7ykyfRmnVQ: Some web_safari client https formats have been skipped as they are DRM protected.
WARNING: [youtube] t7ykyfRmnVQ: Some web_safari client https formats have been skipped as they are missing a url. YouTube is forcing SABR streaming for this client. See https://github.com/yt-dlp/yt-dlp/issues/12482 for more details
WARNING: [youtube] t7ykyfRmnVQ: Some web client https formats have been skipped as they are DRM protected.
WARNING: [youtube] t7ykyfRmnVQ: Some web client https formats have been skipped as they are missing a url. YouTube is forcing SABR streaming for this client. See https://github.com/yt-dlp/yt-dlp/issues/12482 for more details
[youtube] t7ykyfRmnVQ: Downloading MPD manifest
[youtube] t7ykyfRmnVQ: Downloading m3u8 information
WARNING: This video is drm protected and only images are available for download. use --list-formats to see them
ERROR: [youtube] t7ykyfRmnVQ: Requested format is not available. Use --list-formats for a list of available formats