You always have to read Ernest's posts carefully.
A little off-topic (I only stumbled across Ernest's post in another thread; I haven't watched the video and I don't imagine I really care one way or the other about what she might say; I'm not even sure I know which one Emma Watson is), but as long as we're talking about MLK I think it's fair to call him a centrist. Much like Gandhi, Nelson Mandela, and, for that matter, angus.
Progressives like to think he was assassinated because he was moving in an anti-capitalist direction, and that only their agenda would please Martin. Traditionalists like to think that they are the true heirs to King's legacy, and that he might just agree with them on same-sex marriage and the fetus' right to life. What is he in today's political spectrum? Sure, he was outspoken in support of the poor and on labor issues but what would he have thought of the increasing radicalization and fetishism of violence of the New Left? He was a humanist and civil rights activist in response to the condition of the times in which he lived. Nowadays, in terms of the political compass for example, he'd probably be a bit left of center and maybe just in the middle on the authoritarian/anarchy axis. -3, 0 perhaps. Just a guess.