AVI ReComp is a free application for Windows that allows you to recompress your video files and apply them new elements or modifying them.
There are some possibilities, from changing the video size to adjust subtitles, print a watermark, change sound, convert it to other format and more.
The application supports not only files containing audio streams but AVIs without any audio as well. The interface is very intuitive, so you'll find no problem when searching for the conversion you want to perform.
If you usually want to modify your videos but you want to do it in an easy way, AVI recomp can be a good choice.