RSA animate and cognitive media have been making videos since 2009. The videos have been posted everywhere from Boingboing to Facebook. I have even received a few in emails from friends. They are famous for making intricately drawn Youtube videos on fascinating lectures by smart people.
posted before about Pinker, he is a really smart linguist. In this RSA video, which is actually a chapter in one of Pinker's books, he talks about how language is a window into social relations. He then uses the film Fargo to explain what an indirect speech act is and why they are important in every day interactions.
I remember reading a post by a goon on the Something Awful forums saying something along the lines of "If you are a girl at a party and a guy ever wants to show you his guitars up in his room NEVER go." The offer to bring someone up to your room is an indirect speech act. You cannot proposition the other person for sex and one must be coy when doing so. What the white knight goon failed to realize, other than the fact that women have more experience handling propositions for sex then he ever will, is that indirect speech is actually an important part of our language. Anyways I digress, here is the video:
Essentially when speaking to someone who is in a relationship where boundaries are not clearly defined (ex. boss & worker, a date), we must use the imperative (a direct order, "do this") without seeming dominate or breaking the appropriate rules of that relationship.
The reason why we resort to indirectness when there is no uncertainty is because the listener can figure out the speaker's intentions and the whole conversation becomes less awkward than a direct proposition for something. Also there arises the paradox of mutual knowledge vs. shared knowledge. In individual knowledge a group of people know something. In mutual knowledge a group of people know something and they know that other people know it too. As the example in the video suggests, this is how governments are overthrown.
Explicit language creates mutual knowledge. Once again citing the video; the emperor wears no clothes, now that the child has explicitly stated that the emperor is naked, everyone now knows that everyone else knows the emperor is naked, thus changing the state of their knowledge, making the whole situation hilarious. Therefore when indirect speech is used, mutual knowledge is avoided and relationships can (hopefully) still be maintained. This is why we need to be careful when speaking, and at times play games with our language. Fascinating stuff!
The book is The Stuff of Thought, and the chapter is Games People Play.