#!/usr/bin/env ruby

require 'rubygems'
require 'rvideo'

file = RVideo::Inspector.new(:file => "/home/user/r/input.mp4")
file.fps        # => "29.97" 
file.duration   # => "00:40:23.4" 

# rest of the code follows

Ruby Shoes (by why) is intended to be a really simple GUI framework. I don't know how fully featured it is, though.

Some good code samples can be found in the tutorials.

Also, I think shoes powers hackety hack, a compelling programming learning environment for youngsters.