Buffet said he paid a higher percentage in payroll and income tax then his secretary. The article you link to talks about total federal taxes on average. The two don't line up.
The 10 percent of households with the highest incomes pay more than half of all federal taxes. They pay more than 70 percent of federal income taxes, according to the Congressional Budget Office.
That sort of phrasing is so bad it is hard to believe it is an honest mistake. It is put together to make it sound like the top 10% pay more then their fair share. Saying they pay 70% of income taxes without indicating what percent of income they take leaves you without any basis of comparison.
Jay