Protecting urls on digital downloads

I want to sell digital downloads of instructional videos from my Amazon S3 account. Can I do this with Market Press and keep my urls secure and not have them emailed all over? I have been looking at a plugin called S3Flowshield which can be set up to access my Amazon S3 links while they are still protected.

I would like to set it up so that the customer gets emailed an encrypted link to download the video. He would have to login to that page to download the video.

Thank you,