Maybe they areusing two templates per page? The prettier version and the plain printer version. Using an if statement to determine which template to display.
example:
"Action=2" will display the pretty template of the page
"Action=print_mode" will display the printer version.
I guess it could be done that way, their may be a more efficient way of doing this, I am new with this, so it may be beyond me.
Hope this helps.