I’ve been stumped by this before, and found a fix. Right click this link and add it as a bookmark/favorite:
Bookmark it, don’t click it — javascript:if(document.getElementById(‘macdownloadlink’)!=null){window.location.href=document.getElementById(‘macdownloadlink’)}else{alert(‘Go to Google Video to download videos as AVI.’)};" target="_blank
Then, when you are on the Google Video site watching a video that you want to download, just go to your Favorites and select that bookmark. It will pop up the download option for you. This allows you to save the vid as a standard AVI file, instead of Googles ghey GVI file type which only plays in the Google Player.
Yay