The easiest way I know to get a google vid into an AVI is to download it as an AVI instead of FLV. First, create yourself a bookmark in your browser. Any bookmark will do because we are going to be changing it in the text file anyway. Now go to your bookmark location. If you are using IE go into c:_documents and settings_YourUserName_Favorites_Links. Open Notepad and then drag/drop the newly created bookmark into notepad. Now just replace the entire file with this:
Now when you are watching a google vid and you want it as an avi just click your bookmark.