transfer_vids.js

function getByX(path) {
  return document.evaluate(
    path,
    document,
    null,
    XPathResult.FIRST_ORDERED_NODE_TYPE,
    null
  ).singleNodeValue;
}
const cardXPath =
  "/html/body/ytd-app/div[1]/ytd-page-manager/ytd-browse/ytd-two-column-browse-results-renderer/div[1]/ytd-section-list-renderer/div[2]/ytd-item-section-renderer/div[3]/ytd-playlist-video-list-renderer/div[3]/ytd-playlist-video-renderer";
const settingsXPath = "/div[3]/ytd-menu-renderer/yt-icon-button/button";
const addToPlaylistXPath =
  "/html/body/ytd-app/ytd-popup-container/tp-yt-iron-dropdown/div/ytd-menu-popup-renderer/tp-yt-paper-listbox/ytd-menu-service-item-renderer[3]/tp-yt-paper-item";
const closeXPath =
  "/html/body/ytd-app/ytd-popup-container/tp-yt-paper-dialog/ytd-add-to-playlist-renderer/div[1]/yt-icon-button/button";
const playlistContainerXPath = "//*[@id=\"playlists\"]";
const playlistElemSelector = "#checkbox #checkboxLabel #checkbox-container #checkbox-label #label";

function register(id) {
  console.log("> Registering " + id);

  let settingsButton = getByX(cardXPath + "[" + id + "]" + settingsXPath);
  console.log("Opening dialog...");
  settingsButton.click();

  setTimeout(() => {
    let add = getByX(addToPlaylistXPath);

    console.log("Opening selection modal...");
    add.click();

    setTimeout(() => {
      let playlistsDiv = getByX(playlistContainerXPath);
      let playlistId = 0;
      for (let j = 0; j < playlistsDiv.children.length; j++) {
        let playlistElem = playlistsDiv.children[j];
        let title = playlistElem.querySelector(playlistElemSelector).innerHTML;
        if (title === "Actual music playlist") {
          playlistId = j;
          break;
        }
      }

      let checkbox = document.getElementsByTagName("tp-yt-paper-checkbox")[playlistId];
      let close = getByX(closeXPath);

      console.log("Adding to playlist...");
      checkbox.click();

      setTimeout(() => {
        close.click();
        console.log("! Done");
      }, 400);
    }, 800);
  }, 300);
}

let count = 0;

setInterval(() => {
  count++;
  register(count);
}, 1800);