If you've registered the product and signed into Adobe, the component will download and install automatically when you start a project that requires the codec.
I understand the message that you are getting and trying to follow. It happened to me once unexpectedly.
Is this the site that you seek?
If so, I just checked it, and it is working.
By the way, do you have the latest version of QuickTime installed on your computer along with Premiere Elements 10?
The address may be having periodic problems as evidenced by this older online information
Please let us know the outcome.
Add On...I have an Adobe Chat link for program activation, but I am not sure how that applies if at all to feature activation. We will pursue that next if the above does not work. It should.