I use Tubemogul to upload and track all my videos. This chart below shows a bump in viewership on Halloween. What caused it?
It turns out that Rob Zombie was a guest editor on YouTube for Halloween. His first choice was a timelapse rotting pumpkin. It wasn't my rotting pumpkin video, but mine showed up as related (because of the tags) everytime someone watched the one he mentioned. That generated a big boost in views for all my videos.
What's ironic is that Rob Zombie is a good friend of my nephew Brian.