Hi ajborn, the moz-extension:// protocol is used to show internal pages from one of your add-ons, and the left part of the address bar shows which one it's coming from. So that looks like a message from Video DownloadHelper. Some extensions require more privileges than Firefox allows. In that case, a separate program needs to be installed on your system, and the extension sends it commands. I'm nervous about those, too, so I totally understand not being inclined to install the "native application." So far, I've never done it myself. If you want the features of that add-on, I think you need to research the add-on and its author/publisher to see whether you can trust the additional software.