How Download youtube videos From Mobile /Pc Without any Software

To Download Youtube videos 
Just remove ‘m.’ 
Or ‘www.’ From video url and add ‘ss’ infront of it and
enjoy downloading video in differnt qualites..
Example in Mobile : http:// m.youtube.com/watch?v=0LrT8N02vys 
Remove m. & Add ss http://ssyoutube.com/watch? v=0LrT8N02vys EG 
in PC : http://www.youtube.com/ watch?v=0LrT8N02vys 
Remove www. & Add ss http://ssyoutube.com/watch? v=0LrT8N02vys 
Choose 3gp 240p,flv 240p,flv 360p,mp4 360p,mp4 460p,mp4720p etc