Webcam driver that uses an image or video file as the video source

SplitCamera should work for what you need - Free alternative of ManyCam.

Came across this and thought I would contribute the solution that suited my needs.

Open Broadcaster Studio allows you to stream and record many sources layed out in a virtual canvas: you can define sources such as :

• Images, Video, Your Live Desktop, your microphone, Audio Files, your speaker output, ...

Additionally you will Require a plugin To be able to create a Virtual WebCam:

• OBS-VirtualCam provides a directshow Output as a virtual webcam of the virtual canvas which you have defined from the selected sources.
  • The plugin works on Windows.
  • For Linux, you can use the Video4Linux sink plugin for OBS Studio.

Once installed, setup and running: select the OBS-camera source from the webcams available from within the software of your choice.

Cheers!