Find the Youtube video you want.
While the video is playing, goto the top of the page and open WINDOW–>ACTIVITY
Take a look at all the elements of that page (you may have to click the ‘carrot’ to display)
Find the one that is still ‘moving’, i.e. getting bigger and bigger in size.
Double-click on that item specifically.
A new window will open up and the file will download to your harddrive.
The file will likely be a FLASH .flv movie, but you can convert it with Quicktime Pro or VLC or any number of other programs, converting it to an m4v for your iPhone if you want.
Here endeth the lesson.]]>