Add a layer on top of /dev/video*

It is possible to use programs such as vloopback to send video data to /dev/video*

This specification is for extending this ability as well as adding features such as being able to use one web cam over multiple programs as default in Ubuntu.

I propose the following extra functionality be added by default into Ubuntu:
- The ability to use the same web cam device for multiple programs at the same time.
- The ability to feed video data into /dev/video as an alternative to using webcam output
- The ability to switch seamlessly between a video file and a live stream.

Some use cases include:
- A user that wants to use his web cam while talking to multiple users though Amsn, Gyachi, Ekiga, etc
- A user that wants to show a large family movie changes the live stream to play a movie and once finished is seamlessly transferred back to the live webcam stream.