Easy way to download Youtube videos without any software installation

You tube videos can be downloaded in mp4, flv format easily without the usage of softwares. For that, just type 3 in the place of y in the link of the video. For example, www.youtube.com/watch******** should be changed to www.3outube.com/watch******* . Line text matter can be selected with triple clicks made by the left click of the mouse.