Add screencast `screenflow` document

Closes #3
Add a readme for video/ sub-directory
Update readme and tests to reflect github organization change
Add a screencast to the readme
v0.0.6
A few unix/bash-isms

cf. https://en.wikipedia.org/wiki/Cat_(Unix)#Useless_use_of_cat
and man cut
docs about customization
Remove video from the master branch into `screencast` branch

Video is too big and slows down plugin download when in master.
Users complained to this!
Add plugin re-installation instructions to the readme
Update video/README.md