I'm 4 or 5 cars up from the ketchup and mustard every home game, have been for ages. I've seen the ceremony enough that I don't really watch it anymore, instead I watch the people around it. It's fun to watch the reactions, people get excited, cellphones are out taking pictures, people want photos with Kenny, the crowd cheers. Fans that may only make it to a handful of Bills games in their lives make a point of being there for ketchup.
There is a story behind it, Kenny's told me a few times, but I'm not great with remembering fine details so I'll leave the story telling to someone else.