When you watch videos online,a .tmp file is created in your temp folder based on the browser that you use the location would be different.
Will be sharing with you how to copy this .tmp file from the temp location and then rename it to flv where you have your own downladed copy of the video, so that that can watch it again and again when you please.
.tmp file is a very stubborn file and cannot be copied with the normal copy/cut method that window uses,mozilla and IE dont allow you to copy this file,below is the error message that you will encounter.Close Once the browser is closed the .tmp file also gets deleted automatically.
The good part of using Chrome is that it allows you to copy the .tmp file.All you need to do is go the the following path C:\Users\UserName\AppData\Local\Google\Chrome\User Data\Default\Pepper Data\Shockwave Flash\
*UserName = your user login name
Search for the file with .tmp extension which is has the timestamp closest to the time you started the youtube video,now copy it to the desktop or any location you please,rename it to .flv and your done.