As the title says. It's been working fine, but this behavior started yesterday. I've upgraded and reinstalled with homebrew and even tried running the executable downloaded directly from youtube-dl.org. The following code reproduces the behavior I'm seeing:
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$ youtube-dl --flat-playlist --verbose https://www.youtube.com/user/onearmsteve4192/videos
[debug] System config: []
[debug] User config: []
[debug] Custom config: []
[debug] Command-line args: ['--flat-playlist', '--verbose', 'https://www.youtube.com/user/onearmsteve4192/videos']
[debug] Encodings: locale UTF-8, fs utf-8, out utf-8, pref UTF-8
[debug] youtube-dl version 2020.11.01.1
[debug] Python version 3.9.0 (CPython) - macOS-10.15.6-x86_64-i386-64bit
[debug] exe versions: ffmpeg 3.3.3, ffprobe 3.3.3
[debug] Proxy map: {}
[youtube:user] onearmsteve4192: Downloading channel page
[youtube:playlist] UU3x3gDTqUYy_bFZWS-U_mZQ: Downloading webpage
[download] Downloading playlist: UU3x3gDTqUYy_bFZWS-U_mZQ
[youtube:playlist] playlist UU3x3gDTqUYy_bFZWS-U_mZQ: Downloading 0 videos
[download] Finished downloading playlist: UU3x3gDTqUYy_bFZWS-U_mZQ
The flag --flat-playlist just tells it to print the videos instead of downloading them, but it doesn't work without that either (I'm using -x --archive in production but it does the same thing)