Well essentially, its almost impossible to increase video quality like that. Sound you can make sound a bit more clear and crisp, but otherwise video no. Here is the thing though, most players and programs that can run the "compressed avi" Uncompress the file when you select to play it. No the quality will not be as good as the original's, which you can never gain back. It depends really say you zip a video up and compress it. When u extract you should get really close to the videos original quality. Lets say you have a poor quality video, you will not be able to decompress it anymore to make it better. In your case, there may be some bad quality but it depends on where the source came from. Most likely if you were to open it you will get a really close image to how the source original file looked. I am not quite sure how xvid roles though, so i may be wrong about that part.