This can be useful for watching command line progress along with a blog post. Its also possible to copy and paste text from the asciinema, unlike a video.
On Mac Sierra
brew install asciinema
To create a new recording
asciinema rec [filename]
In my case I am installing a session where I install Middleman
asciinema rec middleman
to play the screencast locally
asciinema play middleman
To publish asciinema to the web and the public site you need to create an account using a password-less email registration and login system.
Visit the site asciinema.org, enter email, authorize email and account, then on command line.
and then in browser confirm authorization and finally upload middleman installation
asciinema upload middleman
You can see the warts-and-all Middleman installation on another blog post http://blog.devekko.com/middleman-static-site-generator