try

task4.rb

require 'csv'
require 'ostruct'
doc = "movies.txt"
syms = [:link, :title, :year, :country, 
        :date, :genre, :duration,
        :rating, :director, :stars]
#mas = OpenStruct.new
mas = CSV.readlines(doc, {headers: syms, col_sep: "|"})

def Show_em (array_hash)
  array_hash.each do |unit| 
    puts unit[:title] + " (" + unit[:date] + "; " + unit[:genre] +") - " + unit[:duration]
  end
end

Show_em mas.max_by(5){|a| a[:duration].split(" ").first.to_i}