youtubeの低速化は既出だな
[YouTube] Randomly slow youtube download speed · Issue #29326 · ytdl-org/youtube-dl · GitHub
https://github.com/ytdl-org/youtube-dl/issues/29326

GitHub - 89z/mech: Anonymous API access
https://github.com/89z/mech
どのIssueにもこれ使えって出てくるけど使い方分からん
89z commented Oct 14, 2021
I have an alternative tool with good speed:
PS C:\> youtube -a -1 -v 399 Vp9I_m6znMM
12% bytes=10000000-19999999 10.0 MB/s