Windows Live Movie Maker is a free offering from Microsoft that offers novice and average users the ability to edit video and from there, be able to share/publish it to Facebook, YouTube, eMail, DVD and even custom resolutions. It's a basic editor with very simplified interface, and it's part of the Windows Live Essentials Suite of applications.
Windows Live Movie Maker is a good editor for the price, and it's supported video formats is impressive, when they work; and that's where it gets interesting. Windows Live Movie Maker supports many formats; but what's not provided to the public [regular users] is that Windows Live Movie Maker doesn't recognize those various formats unless the CODEC for that format is installed in the operating system; it's not built-in to Windows Live Movie Maker. And Windows Live Movie Maker doesn't make any attempts to identify or get those codecs for you.
It's a massive flaw in the way video editing should be. If a software vendor says the software they offer is supposed to support X format, then it should support that format right out of the gate— and that's not what Windows Live Movie Maker does.
So, these are some things to know about Windows Live Movie Maker and how to address them…