youpupe.js

let command = null
const observer = new MutationObserver(() => {
  const player = document.querySelector('#ytd-player')
  if (player && !command) {
    command = player.player_
      .getPlaylist()
      .reduce(
        (acc, videoId) => {
          acc.push(`youtu.be/${videoId}`)
          return acc
        },
        ['!sr']
      )
      .join(' ')
    console.log(command)
  }
})

const yt = document.querySelector('ytd-app')
observer.observe(yt, {
  attributes: true,
  childList: true
})