http://www.astrosurf.com/astrobond/ebrawe.htm
A webcam is basically set up to stream pictures over the internet, so it will generally try and compress images, we do not want that in planet pics.
So what this raw mod is, is that it turns off this compression. It is more fiddly definately and for me at the moment it made my mars pics much better, but saturn, i am thinking of trialling it without the raw mod as the colour is not right