how to download any video from youtube no any software

how to download any video from youtube no any software
you go to youtube and search own video and copy video
and follow this step example as that url is http://www.youtube.com/watch?v=JfL2aDEQzJ4
so you do a little work for computer http://www.ssyoutube.com/watch?v=JfL2aDEQzJ4
 (ss) is a widgets .
for mobile thats url is m.youtube.com/watch?v=JfL2aDEQzJ4
and do you this work ss.youtube.com/watch?v=JfL2aDEQzJ4
and download any video any format
you only change m=ss,and          enjoy this trick