Reply To: How to insert a topic words to the video while people presenting
That is quite simple when you know your way around Blender a bit.
The easiest, with simple text, is probably the Video Sequence Editor. Load your video and with your mouse over the Editor space press SHIFT+A and add a Text Strip:
On the right hand side, you can change the words, the. Font, Size, Color, Position, etc. of the text