Camera emulator driver?

Camera emulator driver?

Can someone explain to me how I can use a camera emulator / driver that will allow me to do the following.
While using software like recorder of video chat it will allow me to target content:
Play a video
Play a powerpoint
Include audio from video or mic
Show application window
Online and/or offline (I can record output)
The output type is a camera so apps think it is a camera
Why? I want to present material in applications like paltalk or other video chat software. I would like to be able to switch sources live.
For example:
Intro slide (Powerpoint)
Introduction and Overview (Video)
Content (Slides/Audio)
Content (Play a video)
Conclusion (Powerpoint/Audio)