[Pseudoscience-is-malarkey (OP)]

Although I'm a historian, I am not a teacher. My work is restricted to archival work. When I do speak to an audience it's very brief and uneventful. I'm trying to do some narration for a video I might someday post on youtube. I have the important facts in my head, but when I speak I am constantly second-guessing the words and accuracy. Sometimes im just staring at the mic The irrational part of my brain warns me to not say something totally incorrect that could expose my ego to public ridicule. I wish I had at least some of the word-smith capabilities of firebreathing political figures like Nigel Farage and George Galloway.

[alancalverd]

Some possibilities.

1. Write it all down and polish the words until you can hear them in your head in time with the video action. But beware that formal written English is very different from the natural speech of a real expert - keep asking yourself "would I really say that?"

2. Use a headset microphone. Because it is out of your eyeline you won't get fixated on it, and you'll find yourself speaking to the screen and moving around as if you were talking to another person. You could even have someone in the room and explain the video to them - their silent reactions will help your emphasis and timing.

3. Don't be afraid to use your hands. It's a part of natural speech and the rhythm helps avoid stilted recitation - another advantage of the headset mike.

4. If you are used to lecturing, stand up. If you work in committees, sit down. It sort of puts you in charge of the situation by making it more like everyday work.

Don't despair - it's not as easy as professional actors, commentators and voiceover artists are paid to make it look! A friend of mine graduated from drama school and spent years as a jazz singer and actor before she felt confident to voice other people's films in her own studio.

I'm totally relaxed playing, lecturing, and after-dinner speaking to a real audience, but voicing ad lib to a video or playing an accompaniment to a recorded music track always brings me out in a sweat because the timing is inflexible and there's no feedback. Fortunately a digital editor can splice a dozen takes together, so you can record chunks until you are happy, then spend a few quid having him cut out the ums and errs and stitch it into a seamless and perfectly synchronised performance.   

Now and again, people strike lucky. The original "Mind the Gap" announcement in the London Underground nearly didn't happen because the actor turned up late at the studio and started arguing about repeat fees. As they were running out of time, the recording engineer pushed the button, walked into the booth and said the magic words, just once, for every 2 minutes, for 50 years. You could be next.