Access Privileges prevent me from transferring purchases

I can't seem to transfer purchases from my iPod touch (2nd Gen 16GB) to my computer. I've got a video and some music but when I tell it to transfer purchases it shows them for less than a second and then says I "don't have enough access privileges for this operation." It's my computer and the only one I've used with this iPod. It is authorized, and I've logged in and out of iTunes on both the computer and the iPod. Everything else works, so I think it's just a folder that doesn't have the proper privileges - which I know how to change if I could find the folder. I've tried every folder that I can think of, but I can't find where iTunes holds it's videos, that may be the one. Any help would be appreciated!