For those who have not found the fifth page, I would suggest starting off with the last hidden page that was found -- gathering any possible clues from that and trying those clues -- and working your way back to the other hidden pages, if necessary.
The fifth link is not that hard -- so do not over-think it. Moreover, this thread -- as it is fifty pages -- does have some good guesses, which are at the cusp of finding the page.
Don't give up hope, yet -- some trial and error is, of course, necessary, but once you find the page, it will be that much sweeter (and apparent).
Don't worry about that site. I know a bit of French and can assure you that it has absolutely nothing to do with the Centurions.
Anyways, I'm going to write out everything we know so far about the fifth page. Hopefully this will help us find it faster...
1. We know that once we find this page, it will be different, and perhaps more exciting than the others. Our good friend Jack described it as "that much sweeter (and apparent.)"
2. We know that the clue that is crucial to finding the fifth page is located on the fourth page. It could be hidden in the image itself, or source code.