Wrong ff dork, it's not 14 and revealing "a behemoth exists" in a final fantasy game yeah big big spoiler
"first behemoth scene."
You didn't tell us that a behemoth existed in a FF game. You showed us the first encounter we would have with a behemoth. Lets break down how this can possibly be a spoiler.
1) "First behemoth": Obvious, you've spoiled the first encounter with a "new" enemy within a game.
2) the gif itself: You've shown us the exact scene of which we encounter a behemoth(we'll assume it's not the first), when playing the game now when we see anything that vaguely resembles this scene whether it be a landmark from the background or a particular behemoth in the distance, we can now automatically assume exactly what is going to happen next without any use of imagination, no possible surprises and not a whole lot of theories because we
know what's going to happen.
I'm not saying this is spoiler, especially not a large one. But for people who enjoy being what we'll call "purests" when it comes to something new it can be annoying and you can't simply dismiss their views because you're not that same way. Because to them you showing that gif is like me going up to someone who's anticipating the reading of a book and informing them of a death to one of the main characters.
TLDR: Don't dismiss someone's view on a spoiler so easily. You know better than that.