Can you use javascript to display the text "Downloading video clip..." until the video clip is downloaded to the users PC then switch that for the embed code to display it?

Hey, lookit, me again

Well, technically, you can by using an hidden iframe.
You can post your file upload in the iframe, and let the handling be done in the iframe.

Have a javascript function in your main page, that is ready to be called to hide the text, and when the upload finish, on the iframe load, do a call on that javascript function.

I'm talking from memory, but a believe it's something like

<script type="text/javascript">
top.parent.functionname();
</script>

Of course, replace functioname() with your function.
It could be top.opener, rather than top.parent, I'm not 100% sure, to reach your hidding function.
But this is the road you need to follow if you want to do that.

I know little/no js - need snippet!

well, there is none.
It's a full page, with all the logic you need.

If you don't feel confident enough, may I suggest you to hire a webdev to do it for you.
Try http://www.getafreelancer.com, you will find someone.

You'll find this on Google and free script sites. I'm completely sure if you spend a few minutes looking for it on any major search engine you'll find it.

Had a look - no luck...

google ur problem