Well, I'm pretty sure your upload speed would have a pretty low cap, and should not have much impact on download speed.
But mainly, that is probably the Web Shield working. It re-routes all your Internet traffic through it, thats how it scans things before they land on your PC. So it really is not up/downloading anything. It scanning what you are browsing (Youtube). The "upload" is the WebShield sending something it has scanned to your PC.
How slow is it making your browsing? Is only Youtube affected?
