As surprising as it might seem, the viral nature of YouTube is paying off for advertisers.  Below is a chart of ads that have millions of weekly views on Youtube. 

Want a compairson of traffic?  The largest (I could find) viewership on Swine Flu was a Symptoms of Swine Flue from the CDC with 864,000 total views.

	Last Week	Brand	Campaign	Agency	Current Week Views*	% Change in Views**	Watch the Spot
1	1	T-Mobile	T-Mobile Dance	Saatchi & Saatchi, MediaCom	598,827	-2%
2	New	Trident	Beyonce 100 Single Ladies Flash-Dance	Pretty Green, Initials Marketing	373,706	New to Chart
3	3	Cadbury	Eyebrow Dance	Fallon	363,467	-11%
4	2	Samsung	Extreme Sheep LED Art	The Viral Factory	352,699	-23%
5	5	Philips	Carousel	Tribal DDB	338,672	+4%
6	6	Durex	Get It On	Fitzgerald & Co., SuperFad	263,629	+10%
7	7	Burger King	SpongeBob	Crispin Porter & Bogusky	252,952	+10%
8	8	Geico	It’s the Gecko/ Numa Numa	The Martin Agency, Horizon Media	201,152	-8%
9	New	Boston Bruins	Never Date Within Your Division	Mullen	187,675	New to chart
10	New	Marshall’s	Kelly: The Prequel	Mr Youth	177,746	New to chart
Source: Visible Measures