완성!

function doFirst() {
    barSize = 600;
    myMovie = document.getElementById("myMovie");
    playButton = document.getElementById("playButton");
    bar = document.getElementById("defaultBar");
    progressBar = document.getElementById("progressBar");
   
    playButton.addEventListener("click", playOrPause, false);
    bar.addEventListener("click", clickedBar, false);
}

function playOrPause(){
    if (!myMovie.paused && !myMovie.ended) {
        myMovie.pause();
        playButton.innerHTML= "Play";
        window.clearInterval(updateBar);
    } else {
        myMovie.play();
        playButton.innerHTML = "Pause";
        updateBar = setInterval(update, 500);
    }
}

function update() {
    if (!myMovie.ended) {
        var size = parseInt(myMovie.currentTime*barSize/myMovie.duration);
        progressBar.style.width = size+"px";
    } else {
        progressBar.style.width = "0px";
        playButton.innerHTML= "Play";
        window.clearInterval(updateBar);
    }
}

function clickedBar(e) {
    if (!myMovie.paused && !myMovie.ended) {
        var mouseX = e.pageX - bar.offsetLeft;
        var newtime = mouseX*myMovie.duration/barSize;
        myMovie.currentTime = newtime;
        progressBar.style.width = mouseX+"px";
    }
}

window.addEventListener("load", doFirst, false);