To use this install Docker Desktop and under Dev Environments click 'Create' and when prompted paste the URL for this repository into the box.
Follow through the prompts and then click 'Open in Visual Studio Code' and when it loads up right click on the Dockerfile and click 'Build Image...' and when asked call it 'josephsellers/nextcloud-ffmpeg'.
Go back to Docker Desktop and under Images click the three dots on the image and then click 'Push to Hub'.