Someone that is race X is more likely to vote for someone that is race X
How does that play out?
It "plays out" depending on your assumptions you bring into it. You and others apparently feel black people were racist and voted for Obama because he was black. I suspect that some people did that (just as plenty of people DIDN'T vote for him because he was black), but I think quite a few more voted for him as they felt that he, as leader of the country, would benefit them more than the Republican alternative. Which is not surprising as this, historically, has been the voting trend.
To support this, if we look at 2010 and 2014 midterm elections, we see the same margin we saw in 2012 (and statistically it is probably identical to 2008). Thus, even when Obama himself is not running, the black vote goes in the same percentages towards Dems over the last 8 years. Perhaps that is because of Democrat policies, or other factors, but it seems unlikely that they are being motivated to vote out of racism still.
We are trying to get at the motivation of individuals, apparently, which is extremely hard to quantify and rather ridiculous. It is very easy to claim that Obama - who absolutely demolished his opponents - only won because of racist black people, but the reality is unlikely to be that at all. After all, other minority groups voted for him for reasons beyond race (e.g. young people).
If anything, twylyght's figures show that either Obama being in the White House is forcing black people to vote for white people in midterm elections (see their numbers in 2010 and 2014 as being pretty much identical to 2012) or, as is very likely, black Americans for one reason or another think the Democratic party is more likely to pass legislation that benefits them.
It is almost as if these individuals may be acting on something other than skin color. Hrmmm.
edit: did young people vote for Obama because he was black, too? j/w.