From 13:30 - 14:30, the narrator writes a comment and it runs the call instantly to output the results. Anyone know what plugin he is using for Textmate or Sublime text?
I think you are looking for SublimeRubyEval Plugin.
You can read more about in in this blogpost: http://kevinthompson.info/blog/2013/02/07/execute-ruby-code-inside-of-sublime-text.html