You know what, go to this forum http://forum.doom9.org/forumdisplay.php?f=77 and ask the guys there for help on converting it to lossless RGB avi. Seems there is a way to do it, but I just can't find any clear info on how.

EDIT: It seems that you should be able to open an avisynth script with the software VirtualDub and render it as lossless avi using an encoder called huffyuv. Not 100% sure about this but worth a try.

To make an avisynth script with the video, simply type this in notepad and save as ".avs" file extension, in the same folder where the video file is.

DirectShowSource("SWharmy.mkv")

Just an example, using the filename it had before you remuxed it. :)