I agree with your point that usage of rationality this way exacerbates the problem of straw-vulcanism. I'm not sure the criticism is aimed at the lowest hanging fruit in this case, but your point is well taken.
Your point about the dangerousness of rationality is not on point. I am almost strictly better off in a society in which the members are not at odds than in one where they are at odds. But whether one of the exceptions to that statement applies does not appear to depends on how dangerous individual members are. Unless individuals are so dangerous that mutually assured destruction is an important part of the analysis. And that is currently so unrealistic (at the individual level) that I don't think it is worth talking about.
Your point about the dangerousness of rationality is not on point.
My point is not that rationality is dangerous. It's possible to formulate situations in which increasing the rationality of a population leaves the population worse off, rather like it's possible to formulate situations that reward agents for having priors that would normally be stupid. The fact that you can contrive such situations doesn't constitute a compelling criticism of rationality, which is what makes the video problematic. If rationality really were that dangerous, the implicit criticism would be entirely valid.
It's a brilliant idea: a lecture by a cool modern thinker, illustrated by word-by-word doodles on a whiteboard. Excellent at pulling you along the train of thought and absolutely disallowing boredom.
The lectures' content is pretty great too, although there's a definite left-wing, populist bent that's exploting today's post-crisis hot button issues (they got Zizek, for god's sake) - some might not like it. Regardless, it's all very amusing and enlightening. Been linked to before in a comment or to, but it deserves a headline.
You can start here: http://www.youtube.com/watch?v=dFs9WO2B8uI&feature=relmfu (But they're all worth watching!)