How to Download Youtube Videos Without the application

It's been a lot of sites that provide free tools to download videos on youtube, ranging from online downloader, software, or add-ons and plugins for a browser.
But how do I download videos on youtube without having to install software and add-ons first? you can use javascript to download the video.
The trick is as follows:

1. Go to the video on youtube that you want. For example:
http://www.youtube.com/watch?v=E3keLeMwfHY

2. After that Copy and Paste the following javascript in your browser (Change your browser's URL with one of the javascript below).

Download Regular Quality Youtube Video Direct Links [RQ] :

javascript:window.location.href = 'http://youtube.com/get_video?video_id=' + yt.getConfig('SWF_ARGS')['video_id'] + "&l=" + yt.getConfig('SWF_ARGS')['l'] + "&sk=" + yt.getConfig('SWF_ARGS')['sk'] + '&t=' + yt.getConfig('SWF_ARGS')['t'];

Download High Quality Youtube Video Direct Links [HQ] :

javascript:window.location.href = 'http://youtube.com/get_video?video_id=' + yt.getConfig('SWF_ARGS')['video_id'] + "&fmt=18&l=" + yt.getConfig('SWF_ARGS')['l'] + "&sk=" + yt.getConfig('SWF_ARGS')['sk'] + '&t=' + yt.getConfig('SWF_ARGS')['t'];

Download High Definition Youtube Videos Direct Links [HD] :

javascript:window.location.href = 'http://youtube.com/get_video?video_id=' + yt.getConfig('SWF_ARGS')['video_id'] + "&fmt=22&l=" + yt.getConfig('SWF_ARGS')['l'] + "&sk=" + yt.getConfig('SWF_ARGS')['sk'] + '&t=' + yt.getConfig('SWF_ARGS')['t'];

3. Then press Enter. Then later be asked to save the video file.

4. Click OK and the video will start downloading.

Good luck.