In theory, recording a lecture should be easy - just point the camera at the speaker and hit record. And it is easy - if everything goes right. But there are lots of things that can go wrong - the audio is bad, the lights get turned off for a PowerPoint presentation, the speaker starts pacing across the stage etc. That's why it's so important to prepare everything before the event starts. If you've don't that, then you an be comfortable knowing that the recording will go smoothly.
Check out this article for tips for recording lecture and event videos.