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I understand that one method involves using a Learning Mangement System. Another method involves creating your own Web Site. Installing Wordpress on it, then acquiring some PHP scripts that assist with managing the content. Basically the scripts handle obfuscating the real link. They also facilitate connecting your site to a payment gateway such as PayPal or Google Checkout. Keep in mind that Captivate output files can be rather bandwidth hungry. So depending on your estimated activity, you may wish to also investigate using Amazon Simple Storage Service (S3) for storing your Captivate content.
Having recently worked in this space I can attest that while it's certainly not rocket science, it's also not totally plug and play either. Prepare for LOTS of frustration. Not for the faint of heart. I'm still ironing out details on my own setup.
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