I had the privilege to attend TEDx Tel Aviv. It was a wonderful day. Some (random) observations:
  • 18 minutes are great: short enough to keep the audience attention, but long enough to cover the most complex subject material. Anyone can present their idea in 18 minutes, if you can't, it's the presenters fault, not the audience's intellectual abilities
  • Personal stories are incredibly powerful, especially if they connect to the interests of the audience. "The doctor told me that my daughter will die soon. I did not accept this". You are on the edge of your seat.
  • Polish is not everything. Imperfect English, glitches, as long as your story is passionate and genuine, your audience will forgive you.
  • Many different uses for slides, none of them were speaker notes/bullets: 1) relative proportions between numbers [$250m versus $250bn), 2) setting the mood [screen shots of mountain bike trip surroundings], 3) functional video [mosquitos getting zapped by lasers]
  • Building on that. Slides can be incredibly simple and still be effective. And I mean even more simple than stock image + a few words. 
  • To keep a conference day interesting you need to shift gears all the time. Spectacular presentations, humor, emotional/touching content. Variety keeps up one's attention
  • Related: the power of an emotional ice breaker presentation. My organizational behavior professor in INSEAD was a master at this: start a session with a deeply emotional topic or question, and it makes the audience forget their usual defenses, makes them more receptive/open to subsequent content. Hard to explain why, but it works.
  • Unlike you, yourself, the audience is not really interested in your personal background and history, they want to learn from your ideas and perspectives. Talk less about yourself, talk more about what the audience can learn.
  • Props are great (bottles of algae for example). 
All in all this day was a great presentation experience. Hardly anyone in the audience left the presentation hall, hardly anyone was checking email on their phone/laptop. It is possible to stay a focussed listener for an entire day.