In January 2017, Microsoft ended its support for the Windows Essentials 2012 pack which included Windows Movie Maker. You can no longer download Movie Maker directly from the Microsoft website.
Windows Movie Maker Download Instructions
*UPDATE* Microsoft has now removed the Windows Movie Maker web installer file, and disabled the online installer entirely.
Here is an offline installer for Windows Essentials 2011. The Movie Maker in this version does still support full HD editing, but it is slightly outdated otherwise.
I will try to find an offline installer for Windows Essentials 2012, watch this space for updates.
EDIT: Here is a download link for the English US version of the Windows Essentials 2012 program. It may not work on every computer!