Setting up.

First of all you need to make sure you have your links task bar.

Do this by going View > Toolbars > Links.

Your links bar should look similar to this:

Now that you have the links bar you need to save the link below as a favorite.

Get YouTube video

To do this you right click on the link above and select Add to Favorites... as shown below.

After clicking the Add to Favorites... the box below will pop up and you should click Yes.

After clicking yes you will see the following box.

Select Links from the drop down box and click Add

 You should now have the "Get YouTube video" link like below. 

 Using.

Now that you have finnished setting up the Favorite in you browser you are ready to save your YouTube video.

Go to the YouTube video that you want to save. Once there click on the "Get YouTube video" link.

After clicking the link the box shown below will pop up. This box is informing you that there is a Information bar at the top of the page. Click close.

 Left click on the Information bar and click "Download File..." as shown below.

After clicking Download File the page will refreash itself and you need to click "Get YouTube video" once again.

Once you have clicked it again the box shown below will pop up. Click Save.

The Save As box will pop up and you can browse to where you want the video to be saved.
Don't forget to choose an appropriate file name before clicking save.

The file will now download to the place you chose in the previous window.

 All you need to do now is to browse to the place that you downloaded the file to double click and enjoy.

 These instructions based on information at the following website.
http://googlesystem.blogspot.com/2008/04/download-youtube-videos-as-mp4-files.html