Hi. We wish to have the Username, Email and Password fields embedded on an External Landing Page for our online marketing campaign.

Visitors on the landing page would then enter in a Username, Password and Email which would automatically register then onto my site and then give them the ability to download an eBook and watch a few videos.

Can this be done? Is there anyone here who knows how to do it? We are willing to pay.

I believe (if you mean external from Joomla) you would need to create a plugin to capture the details and input them into the database yourself.