@cpaine: Windows has a built-in zip tool which shows the content of a zip file as if they were in a normal folder. But it’s not. You need to unzip the file, and extract the content into a local folder first. Especially if the zip contains an executable, you can’t run it directly in the zip file.
There are many ways to unzip a zip file: you can right click on the .zip file and select ‘Extract’; or you can double click on the zip file and drag and drop the osFirmwareUpdater folder onto your desktop. I actually recommend using a third-party tool like 7-zip because Windows’s build-in zip tool is very primitive and can’t even handle .rar, .7z files, or large zip files. It’s a pretty crappy tool.
Anyways, once you have unzipped the content, go to the osFirmwareUpdater folder -> windows subfolder, and double click on osFirmwareUpdater.exe.