I'm regularly asked to present short pieces on film about new innovations, product introductions and other such stuff.
The scenario is generally the same; I have a vague idea beforehand of what the subject matter is, but it's only when you are on the spot and talking to the person responsible for the idea/product that you get a true picture of what it's all about. I then have to - in a matter of minutes - come up with a story, briefly rehearse and then present it to the camera before moving on to the next one.
I presented the Philips stand tour at the IFA in Berlin for five years in a row. I've also covered a major research exhibition (recording almost 40 short films in the space of two days) and made a series about concepts designed to help improve training techniques for swimmers.
After more or less every match I attend for UEFA.com, I carry out filmed interviews with players. Technically I'm not actually on camera, although you can hear my voice and now and again see a bit of my hooter... Here's one of many examples: