Causes for synchronized traffic fluctuations across all SEs?

[andheresjohnny]

Maybe someone brigher than myself can give some insight. I have a video blog where for several days I may see SE traffic such as Yahoo=4000, Google=3500, MSN=1000.

Then for the next several days my SE traffic starts to goes down across the board until it gets to numbers such as Yahoo=1500, Google=1000, MSN=400.

Then they go up again.

The thing that baffles me is that the search engine traffic appears to rise and fall together. Google, Yahoo and MSN always seem to move together in the same direction.

Any ideas why this might be? Does anyone else see similar movement?

Thanks.