One of the marks of true expertise and skill is making something very difficult look easy and effortless. It can take a long time and a lot of work to give the impression that something is natural and everyday for you. It takes even more work and practice to make something look spontaneous and unrehearsed. This is as true of giving a technical presentation as it is of playing a sport or a musical instrument, dancing, singing, or cooking. Oddly, some people seem to think that presenters are all "just naturals" who don't practice, rehearse, or plan.
There are two problems with thinking that. The first (and the smaller one) is that it doesn't give enough credit to the hours of work that goes into producing that "off the cuff" presentation you so enjoyed. The second (and by far the bigger one) is that it leads you to think that you couldn't be a presenter. And that would be a loss. Presenting, even in the smallest of contexts, makes you better at whatever you're presenting about. If you do a presentation on Windows Phone development or Visual Studio Extensibility or the like, you will know that subject better when the presentation is over. It also generally helps your career, gives you a chance to meet people and help them, and if you're lucky will also get you a chance to travel to marvelous places and meet even more people.
One of the terrific people I've been able to meet thanks to the speaking I've done is Guy Smith-Ferrier. He's really good. He's always been generous with slides and downloads on his website, and he really knows his stuff. And now he's made a series of videos
to show anyone - really, anyone! - just what it takes to be a presenter. He covers a number of things I've never seen in talks of this kind, like choosing your topic wisely. They total a little over 2 hours and are well worth your time if you're thinking of trying presenting or (more likely) you wish you could and think you can't. You can watch
them on the UGSS site or download
them if you prefer (search for speaker.)
Once you've watched these, you will understand what it seems the great speakers just "happen" to be doing. And you can do those things too. You can be a presenter if you want - it's no harder than learning to code. Guy's straightforward way of laying down the truths behind great presentations will take you where you want to go.