Good quality comes with long render times, and there is nothing you can do about it in any program you use. I would suggest you to convert the avi file to a different format to compres it, like MPEG-4 to get the best quality with the lowest bitrate. Just google for "avi to MPEG-4 converter" and you should get loads of options. Experiment what quality you can get under those 5mb. Also I would suggest you to do some reading about this topic to better understand how all of it works to get the best results.

Oh yes, and not only colour but the highest available resolution (as well as the terrain geometry) and already projected on the terrain!