A useful feature in slideware that many presenters are not aware of is the B key. If you don't know what I'm talking about, try it out now: Start a presentation, then press the B key. What happens is that the screen will turn black - hence 'B'. Press the key again and the slide will be displayed again.

Videos can enliven a presentation. They can be used to illustrate something that would be hard or impossible to recreate on stage or with static slides. So there's nothing wrong with showing a video, presuming it is short.

But how long is "short"? Think back to the last time you watched a video in someone's presentation. 30 seconds are fine. One minute, however, can already feel long. Get to 3 minutes and all you want is for the video to end.

Why is that so? Why can't we bear to watch a 5-minute video but sit through entire movies which are 90 minutes or longer?

The other day, I was watching a TED talk by a French speaker. He was speaking English, but with a heavy French accent. At times, I could only understand a word he'd used once I had heard the complete sentence. Now, not everyone can speak perfect English (certainly not me), but an accent like this can make it really hard to follow what you're talking about. We've had that discussion with some of our TEDxStuttgart speakers who often would like to speak in English, hoping to reach more people that way, even though their English wasn't that good.

TED is known to only upload the talks that they consider good, even skipping some from their own conferences. So why did they decide to publish this one?

While discussing typical lengths of various types of presentations during a course recently, I got the question whether it actually makes sense to do a 60 minute presentation on any topic.

That's a great question, well worth considering. Why do traditional conferences still insist on reserving 60-minute slots for presentations?

What makes a TED talk special? Is it the use of spectacular props or the masterful delivery? These are the sorts of questions that I have been asked - somewhat anxiously - recently.

TED's motto should give you a hint. It reads "ideas worth spreading". For TED, the idea is at the heart of a TED talk; all else follows from it.

Chris Anderson, curator and organiser of TED, explains this in more depth in a video titled "TED's secret to great public speaking". Before you read on, I encourage you to watch it. It's only 8 minutes long and embedded below: