They're just from Wikipedia.
Sure, I guess there could be somebody getting their jollies by just coming up with random numbers, but I think their is some meaning to them. Even if it's simply tickets sold, it counts for the team's coffers.
Here's another video (or I suppose I could just watch the one that shows a few hundred and just assume it's like that 17 times a season).
• Video Link
Sure, the 27,000 seat stadium is nowhere near full, but I never claimed they had strong fan support; I claimed their average was within the numbers somebody had mentioned.