onVideoComplete

main.js

await this._page.evaluateOnNewDocument(() => {
      let checkWatchTimeFunc = () => {

        let currElem = document.getElementsByClassName('ytp-time-current');   //grab the element showing current play time
        let maxElem = document.getElementsByClassName('ytp-time-duration');   //grab the element showing total play time

        if (
          currElem.length > 0 && maxElem.length > 0               //check if there are any such element
          && currElem[0].innerText === maxElem[0].innerText       //compare the value between the 2 elements
        ) {
          window.videoEnded();                                    //video ended, trigger event
        } else {
          setTimeout(checkWatchTimeFunc, 5000);                   //perform the same check 5 seconds later
        }
      };
      
      checkWatchTimeFunc();
    });