You'll have great difficulty contacting the people behind that site because it's operating illegally. (i.e.they've not paid for the broadcast rights to any of the programmes which are there). That's why they've used a privacy service to hide the names of the people who've registered the site's domain name.
Most of what is shown will be off-air recordings made by people in their own homes. If someone who contributes content to that site records the output of, say, their Sky box, while watching with subtitles on, those subtitles will be carried over to the recording and there's then no way of removing them.