36101 Protect folders

I have videos for download that are in zip format stored in a single video folder. I need a solution to protecting these files from download managers. For about the last year now we have been collecting orders from paypal and storing them in a db with paypal's IPN. Then on a download page (that is filtered by their username), they have download links. They click the link and the file begins downloading. However, if someone was smart, they could view the source and could get the exact URL for that video and give it to all their buddies. In addition (and this is the main problem) recently a customer was using a download manager and somehow gained access to the entire folder. It sounds like he was pretty much using some kind of FTP type thing and could see/download all the files. This is obviously a serious problem for us. We need a solution that will allow members to download the videos but restrict people from viewing the whole folder. Their is only one FTP account that is shared between me and the owner of the site, so he is not somehow getting FTP access to the folder (but in a way he is). I need someone with a simple solution as there are three mirror sites. IF YOU PLACE A BID, PLEASE PMB FOR YOUR IDEA. Only one of the sites has cPanel access. I WILL NOT ESCROW PAYMENT BEFORE PROJECT IS COMPLETE. DO NOT BID IF YOU ARE NOT OKAY WITH THIS.