During the 2008 presidential campaign, people on YouTube consumed a billion minutes of Barack Obama campaign videos. That adds up to almost 2,000 years.

This year, Obama and GOP presidential candidate Mitt Romney are on the way to leaving that figure in the dust. The campaigns are constantly releasing new web videos.

Lee Rainie, who directs the Pew Research Center's Internet and American Life Project, remembers when the rule for successful online videos was repetition.

"The old conventional wisdom was that you had to hammer home the same message consistently a lot of times before it would actually sort of penetrate the consciousness and begin to shape the opinion of voters," Rainie says.

Now those days seem quaint. Today it's all about constant stimulation, everywhere, all the time.

"People's attention is so fragmented, their sources of information are so fragmented, that consistency doesn't necessarily have the same power that it might have had in days gone by," Rainie says.

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