Lecture recording on a computer with webcam on Ubuntu

Question

I wish to deliver lectures using LibreOffice Impress, and record them while sitting at home. Therefore I wish to have the following:

1. Play the presentation using LibreOffice Impress
2. At the corner of the screen, there should be my face captured by the webcam.
3. Meanwhile, the mic would be on for taking voice input.
4. All the above three should be recorded into a video file and if possible broadcast it on YouTube.

How to do this on Ubuntu?

Comment: 16.04 / x64.