Help Video resolution question!


Hi! I own a Sony Eriksson Xperia Play which runs an Android 2.3. Recently I used Media Go to transfer a DivX file to the phone. It took ages to tranfer and the resolution was terrible. Ironically if I watch YouTube the picture is crystal clear. Am I trying to use the wrong file type? and/or Do I need a better app for running video files? If someone could please steer me in the direction of a better file type to use or an app that would fix this I would be most thankful. :)