I'll just add one or two things to the good advice you've already been given...
[Olly Lawer] "One of which is an ex broadcaster who boosts a wealth of experience. I've never seen her work but pressume it's good."
That's a big assumption to make. You need to see this person's actual work to know whether they are really competition to you, quality wise. Some of the worst production people I know are "former broadcasters with a lot of experience."
[Olly Lawer] "Crease payments and the video is deleted from YouTube, thus their site. How do I protect myself from them just using real player downloader and grabbing the video for themselves?"
You can't. Once a video is on YouTube (or any other video hosting website) it can easily be downloaded by someone who knows what they are doing, usually a simple browser plugin will do it with one click.
If your work is good, you can justify your rate.
T2
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Todd Terry
Creative Director
Fantastic Plastic Entertainment, Inc.
fantasticplastic.com