Jordy,
Yes when printing out a web page on a printer. We are using your gallery and lightbox plugins on an e-commerce site and customers like to print web pages. If it was just us working on the site here then yes a screen shot would be fine. I just thought it might be indicative of something bigger that you might want to look into. We currently have the lightbox plugin deactivated but I did turn it on and print a page from our site to PDF so that you can see it.
It can be grabbed from here
Thanks,
Bob