The checkbox on 1040 line 7 is not for Schedule B. It is for Capital Gains on Schedule D. If you have any Capital Gains on a 1099Div box 2a or qualified Dividends in box 1b. Those go on Schedule D and get taxed at capital gains rate.
If you have capital gains or qualified dividends the tax is not taken from the tax table but is calculated separately from schedule D. The tax will be calculated on the Qualified Dividends and Capital Gain Tax Worksheet. It does not get filed with your return.
