Re: is this possible...
I would create a php inlude page, then replace the portion of the home page code with it. That way if you program everything correctly, you could replace the video by simply uploading a new one with the same name..
<?php include (TEMPLATEPATH . '/Name of page here.php'); ?>
Like a text widget, this page "Name of page here.php" should only include the code necessary to run the video (no html, head,body tags).
Or you could place a widget in that position in the theme then just edit the widget..