To edit video you can edit them by windows movie maker if you have windows OS. For Details vist www.microsoft.com/windowsxp/downloads/updates/moviemaker2.mspx .   To edit Avi  files install Avidemix. You can even edit, Mpeg, Mp4, Asf. Download it for free from, http://avidemix.souforge.net .

Video Spin : You can install Video spin from www.videospin.com/redesign if you have windows OS. You can upload the edited videos to youtube and other video sharing sites in flv format. Create scrolling titles with, Title Editor.

Video joiner :-  If you want to edit parts of video files, in different formats and join, then download free video joiner from www.freevideojoiner.com . Browse  videos in the system with Add , Remove. It sopports, Avi, WMV, MOV, MPEG, MPG.