How do I improve the performance of jquery append method?

I am using jquery to show video on website. I have perfomance speed issue for append() How can I improve the perfomance? Any comment would be appreciated Thanks

function viewvideo(videoid) {
//set vidoe in play-video page
varVideoid = videoid;
$("#video").empty();

var data = Ajax("../Ajax/Webmethod.aspx/getviewvideo", { videoid: videoid });
var str = '';


if (data.videourl.indexOf('youtube') == -1 && data.videourl.indexOf('youtu.be') == -1) {
    str += '<video id="myvideo" width="420" height="300"  autoplay="autoplay" ">';
    str += '<source src="' + data.videourl + '" type="video/mp4">';
    str += '<source src="' + data.videourl + '" type="video/3gpp">';
    str += '<source src="' + data.videourl + '" type="video/m4v">';
    str += '<source src="' + data.videourl + '" type="video/x-ms-wmv">';
    str += '<source src="' + data.videourl + '" type="video/webm">';
    str += '<source src="' + data.videourl + '" type="video/quicktime">';
    str += '<source src="' + data.videourl + '" type="video/ogg">';
    str += '<source src="' + data.videourl + '" type="video/mpeg">';
    str += '<source src="' + data.videourl + '" type="video/x-matroska">';
    str += '</video>';
}
else 
{

    str = data.videourl.replace(/(?:http:\/\/)?(?:www\.)?(?:youtube\.com|youtu\.be)\/(?:watch\?v=)?(.+)/g, '<iframe width="420" height="300" src="http://www.youtube.com/embed/$1?autoplay=1&modestbranding=1&autohide=0&showinfo=1" frameborder="0" allowfullscreen></iframe>');}
$("#video").append(str);
.
.
.
}

$("#video").append(str);