There are 2 ways to get around this:
A) force them to be downloaded and not streamed. I don't have the info on this, but I can pull it up if need be. My tech stated that is what he does on paysites.
B) Follow what microsoft says and use
https:// you can get free ssl certificates that work on most machines(90%+ by default for free), and if you pay a small fee, ones that will work on 99% of them by default. By default, I mean the person doesn't have to accept the certificate or install it.
ZoiNk