Convert flv file so I can edit it using Windows Movie Maker? Can I do it for free????

I downloaded some vid's of YouTube and I need to edit them using windows movie maker.

But the files aren 't cooperating. What program can I use so I can change the FLV file to something that will work????

FLV to Video Converter Pro 2 is a conversion tool which converts Flash video (FLV) to video and audio. It supports outputting AVI, MOV, WMV, MPEG, MPG, MP4, MP3, etc. which can be played on your tech toys like iPod, iPhone, Apple TV, Zune, Xbox, Zen, 3G mobiles, DVD VCD, SVCD, and so on. This FLV converter supports FLV types including FLV file encoded with H.264, On2 VP6 FLV, Nellymoser FLV, and Sorenson Spark FLV. In addition to this, it provides a set of powerful functions like video trimming, cropping, image & text watermark adding and encapsulated YouTube FLV Downloader and the calling icon was added into the main interface.