If you want to get high quality video ,u can convert the avi video to FLV with E.M. Youtube video download tool.
then upload it to youtube.
If u make or edit a video on windows movie maker,u need to save the video as avi video on windows movie maker, then convert the avi video to FLV with E.M. Youtube video download tool.
How to save video on windows movie maker? here is a good way for u.
http://www.microsoft.com/windowsxp/using/moviemaker/create/savetopc.mspx
http://www.google.com/search?hl=en&q=%22E.M.+Youtube+video+download+tool%22&btnG=Google+Search
(1)It can search any flash video from many websites at the same time ;
(2)Download youtube video fastly and easily;
(3)Convert flv video to any audio include MP3, wma,wav,ac3,mmf,amr,ogg,aac..., to any video formats include 3gp,avi,wmv, mpg,mpg4,asf,swf,h264,mov,jpg, that can be support by PSP,iPod,iPhone,Apple TV video,iTune,MP3,MP4,Zune,Cellphone,Digit... camera,DV,CD/DVD/VCD/SVCD.
(4)Burn flv video to CD/VCD/SVCD/DVD disc easily and fastly;
(5)It still can repiar and capture RTMP video streams.
(6)Total video player that can play any video or audio.