The youtube charts seem a little strange...
When I go directly to the chart, and select "most viewed videos of all time", I get no entries whatsoever (though there is no problem looking at week-by-week charts).
If instead I click
that link Vonhelmet posted and select "worldwide",
the number one video is "Waka Waka for Africa" or whatever (that abysmal World Cup tune by Shakira), with 490 million views. However, if I
google search for most viewed youtube videos, it turns out that there are other more watched videos, with some Justin Beiber song at the top ("Baby") having 780 million views.
Is there any way to view the actual list of most watched videos in 'real time'?!