Feature and motivation

This is an update in part of SeleniumHQ/docker-selenium#2458 - Optimize video recorder containers. It will something like FFmpeg is installed an run in same Node container.
Currently, in Dynamic Grid, the video container always spawns together with the Node browser container.
Via CLI config (or TOML config) passing value as false to disable this container. The video recording process will be triggered via Env variable.

Usage example

--docker-video-image false