Videri quam esse is a Latin phrase meaning 'to seem, rather than to be'.
It is the signature of a Flamer/CCer and member of the Veritas and Project Lucere on fanfiction.net who frequents the fandoms of Percy Jackson and the Olympians and Artemis Fowl.
She explained to one fanfiction author curious about the phrase: "It's sort of like a disclaimer for my reviews. Just like when you write a story, you put a disclaimer up to say that you came up with the story (along with a million other brain-dead fangirls), but the characters belong to so-and-so, I put that up to say: 'See, up there, where I told you that your story was shitty? That's my opinion, and may or may not be shared by other members of this site. But where I pointed out the grammatical and spelling errors? I didn't come up with those. The English language did."

When you eat dirt for the first time and leave your family to build a shack in the woods