startPictureInPicture.js

// startPictureInPicture.js
(() => {

const getVideos = (doc) => {
  let videos = Array.from(doc.getElementsByTagName("video"))
  const iframes = doc.getElementsByTagName("iframe")
  for (const iframe of iframes) {
    try {
      videos = videos.concat(getVideos(iframe.contentDocument))
    } catch (e) {
      console.warn(iframe)
    }
  }
  return videos
}

const startPictureInPicutre = () => {
  const videos = getVideos(document)
  if (videos.length === 0) {
    console.log("No videos.")
  } else {
    const getKey = (i) => `ok${i === 0 ? "" : i}`
    const clearOKs = () => videos.forEach((_, i) => void delete window[getKey(i)])
    videos.forEach((video, i) => {
      const key = getKey(i)
      console.log(`${key}: `, video)
      Object.defineProperty(window, key, {
        configurable: true,
        get: () => {
          video.requestPictureInPicture()
          clearOKs()
        }
      })
    })
    console.log("ok[i=0] ?")
  }
}

startPictureInPicutre()

})()