There are two answers to this question (and I haven't read the whole thread so my apologies If I repeat something)
1) most blacks have voted dem ever since the handouts of the New Deal
2) If Obama was white or Hispanic he would get almost the same percentage of voters who are black
3) however, the fact that he was black caused many more blacks who had not voted in the past to show up and vote. we saw that when a 10 term congressman lost for the first time in Cincinnati (Steve Chabot). Blacks voted dem at almost the same percentages as they had in 2006 (lock step welfare socialist) but lots of new black voters gave Steve Driehaus (who claimed to have about the same agenda as Chabot). when Obama was not on the ticket in 2010, Chabot easily won though blacks voted welfare socialist at the same high numbers. Far less of them showed up.