I have many questions when it comes to FNAF but my first one has always been: if someone was arrested, why is there even a game?
I know after the first game, people wanted to theorize that there was no real security guard or even Fazbear's Pizzeria; we were actually playing as the murderer in a never ending nightmare of a guilty conscience. Really, the theory would have made sense had there not been two other games that pointed in a completely different direction.
It is points like this one that really makes me doubt that Cawthon had any intentions to turn the game into a franchise, thus not really thinking things through.
But, wait! People get convicted of crimes that they didn't commit all the time, you say. True, but there is a second clipping prior to the one shown that says the man convicted was caught on video surveillance footage taking kids to the back room.
It has already been decided that the murders happened before FNAF 2 and, despite initial thoughts, the game seems to be linear, yet games 2 and 3 suggest that someone else killed the five children. If that's true, what's the point of mentioning that someone has been arrested and charged for the murders? There is no mention anywhere else in the game that perhaps the wrong person was convicted and the killer still out there....you know ,because Springtrap....
The mention, whether true or not, does nothing for the plot of the story at all.