Original blog post - http://blog.alexellis.io/live-stream-with-docker/
How do I rebuild the image from scratch?
This will take several hours on a Raspberry Pi Zero - but less time on a Pi 2 or Pi 3. You can edit the Dockerfile for a Pi 2/3 and change RUN make to RUN make -j 4 to take advantage of the quad-core processor.
$ git clone https://github.com/alexellis/raspberrypi-youtube-streaming/