Just a hack that goes into the teaser field on a video

mj_hack.html

<script type="text/javascript">
var primaryId = "1960";
var alternateIds = ["1647", "1648", "1649", "1642", "1637", "1629"];


function chooseVideo(){
    var watched = localStorage.getItem("mj_video_variants");
    if (watched === null) {
        watched = [];
    } else {
        watched = watched.split(",");
    }

    // If the primary video has been seen, or on 20% of new plays, show an alternate.
    if (watched.indexOf(primaryId) !== -1 || Math.random() < 0.20) {
        var unWatched = [];
        for (var index in alternateIds) {
            if (watched.indexOf(alternateIds[index]) === -1) {
                unWatched.push(alternateIds[index]);
            }
        }
        if (unWatched.length === 0) {
            watched = alternateIds;
            watched.push(primaryId);
            unWatched = watched;
        }
        var randomIndex = Math.floor(Math.random() * unWatched.length);

        videoId = unWatched[randomIndex];

        var srcHTML = '<source src="http://v.theonion.com/onionmedia/videos/videometa/' + videoId + '/zen_mp4.mp4" type="video/mp4"><source src="http://v.theonion.com/onionmedia/videos/videometa/' + videoId + '/zen_webm.webm" type="video/webm">';
        var videoEl = document.getElementById(primaryId);
        videoEl.innerHTML = srcHTML;
        watched.push(videoId);
    } else {
        watched = [primaryId];
    }

    localStorage.setItem("mj_video_variants", watched.join(","));
}

if (typeof videoId === 'undefined') {
    var videoId = null;
    chooseVideo();
}

</script>

Couple notes, I might be wrong:

• line 23: do you need a watched = []; here?
• line 25: i think it's just Math.floor(Math.random() * unWatched.length)