Once opened go to “File” at the top right hand corner of your screen and select “save as”. If you have no folder already assigned for video downloads then open one first. The computer will then save it for you so that you can watch it whenever you wish.
You may also find that your computer puts up a message asking you what you want to do with the file. It will give you some options such as “save” or “view now”. Here you would select “save” and the computer will then do the work for you, just make a note of where it is saving it.