Is there a shell extension for Windows Explorer that adds a new context menu item, which allows to unblock the downloaded file? It should work exactly as I would open the file properties and click the Unblock button.
Ideally, such a shell extension should also display an overlay icon to indicate that the file is still blocked.
Best Answer
There's a tool from Sysinternals called streams.
This page describes how to use it. It doesn't add an option to the context menu, but does allow you to unblock a number of files at once.
I've also found this post which gives a registry file that will do the trick:
which is probably closer to what you want. Copy it into Notepad, save it as something.reg on your desktop, and double click to add it to your registry.