video.rb

class Video < ActiveRecord::Base

  default_scope :order => 'id DESC'
  named_scope :processed, :conditions => { :processed => true }
  named_scope :unprocessed, :conditions => { :processed => false }

end

video_test.rb

context 'Given videos' do
  setup do
    # Add some processed and unprocessed videos to the database.
    [ :uploaded_video, :processed_video ].each do |factory_type|
      3.times { Factory(factory_type) }
    end
  end

  should 'sort newest videos first' do
    Video.all.should == Video.all(:order => 'id DESC')
  end

  should 'retrieve processed videos' do
    Video.processed.should == Video.all(:conditions => { :processed => true })
  end

  should 'retrieve unprocessed videos' do
    Video.unprocessed.should == Video.all(:conditions => { :processed => false })
  end
end