As with many things, the solution is ffmpeg. After I got that upsell thing when I tried to download a video about a week ago, I found the correct ffmpeg incantation, mostly out of spite for Twitter. If you find the m3u8 request in devtools on a tweet, you can use something like the following:

  ffmpeg -i 'https://video.twimg.com/ext_tw_video/1846357395959615488/pu/pl/ecNx-sTzYA9doHYO.m3u8' -analyzeduration 5G -codec:a libmp3lame -b:a 96k output.mp4

(if anyone runs that command...you're welcome for the meme, unfortunately I don't know where it came from)