I seriously dought that the Mozilla Foundation would charge for any of their products.
For one they are huge supporters of the open source thing. And there are no commertial browsers (that I know of). Nobody is going to use a commertial browser when there are so many free ones. Preveiw just means its a release candidate. Besides , People already have seen the code and teqniques and it would be very simple to recreate the browser and people would use the recreation. Mozilla won't and pretty much can't charge.
/ –
