One of the great things of being in Dagstuhl is the fact that every evening the only thing that we can do is to gather together over cheese and wine and talk. As part of one of these wine conversations, Gerhard Weikum told us about the definition of the "anytime" talk: a talk that can be interrupted at any minute and still allow the attendants to get the main message of the talk. (For the non-initiated: an "anytime algorithm" is an algorithm that can be stopped at any point and return the best possible outcome that would be possible to get within the time limit.) This is in contrast to the "good movie" talk, which, as in a good movie, is intriguing throughout but makes sense only at the very end :-)
I think that I naturally prefer the "anytime" talk, but (a) it needs much more preparation, and (b) may be bad for job candidates (how good can it be if you can explain the solution in 2 minutes). Furthermore, I do not know how well it will work for teaching. It does work great for research talks when interaction is expected and encouraged. The "good movie" talk works best when the time allocation is prespecified, and there is no interaction with the audience. For example, TED talks tend to be "good movie" talks, where the message comes across strongly at the end of each talk.