💡Project: Exploring Youtube's .JS

• We have not explored much of Youtube's .JS yet (million characters)

• We could modify any separate component URL through forwarding it to a local URL.
  The largest component is Youtube's player JS https://www.youtube.com/s/player/4918c89a/player_es6.vflset/en_US/base.js
  (embedded version: https://www.youtube.com/s/player/4918c89a/player_embed_es6.vflset/en_US/base.js )
  But we might not adjust the user's current URL itself (as seen with ctrl+U) before it runs
  ( Firefox can filterResponseData (intercept requests), while Chrome will require an "extension is debugging this tab" infobar. )

Yet we only have overridden some of youtube's 1000+ Experiment flags ( #4143 & appearance.js Line 4 )

• Just like uBlockorigin rules

• Compare: https://github.com/LuanRT/YouTube.js/

• Youtube's other components:
  https://www.youtube.com/s/desktop/1daead2b/jsbin/lottie-light.vflset/lottie-light.js
  https://www.youtube.com/s/desktop/1daead2b/jsbin/worker-serialization.vflset/worker-serialization.js
  https://www.youtube.com/s/desktop/1daead2b/jsbin/worker-performance.vflset/worker-performance.js
  https://www.youtube.com/s/desktop/1daead2b/jsbin/scheduler.vflset/scheduler.js
  https://www.youtube.com/s/desktop/1daead2b/jsbin/network.vflset/network.js
  https://www.youtube.com/s/desktop/1daead2b/jsbin/spf.vflset/spf.js
  https://www.youtube.com/s/desktop/1daead2b/jsbin/web-animations-next-lite.min.vflset/web-animations-next-lite.min.js
  https://www.youtube.com/s/desktop/1daead2b/jsbin/custom-elements-es5-adapter.vflset/custom-elements-es5-adapter.js
  https://www.youtube.com/s/desktop/1daead2b/jsbin/webcomponents-sd.vflset/webcomponents-sd.js
  https://www.youtube.com/s/desktop/1daead2b/jsbin/intersection-observer.min.vflset/intersection-observer.min.js
  Embedded:
  https://www.youtube.com/s/player/4918c89a/www-player.css
  https://www.youtube.com/iframe_api
  https://www.youtube.com/s/player/4918c89a/www-widgetapi.vflset/www-widgetapi.js
  https://www.youtube.com/s/player/4918c89a/player_embed_es6.vflset/en_US/captions.js

Start with js&css/web-accessible/www.youtube.com/appearance.js and compare the existing experiment-flag overrides with the listed YouTube component URLs and LuanRT/YouTube.js. Narrow the exploration to one component or interception target and define a reproducible supported outcome; the issue currently names no test or acceptance criteria.