"The big thing that got me was meeting Travis Walton because I'd seen the movie based on Travis's life," said Ryder of making the program.
"I believe Travis was abducted absolutely. But you see other people who have claimed that they've been abducted and it looks just like they are coming back from a day walking around the Trafford Center, all jolly!
"Travis looked like he had post-traumatic stress or had just walked out of a Vietnam battlefield. He looked grey and it really affected him - you could see that from his interviews."
He added: "Governments are definitely hiding stuff. I mean I know they are. It's a fact. I think it's because they really think they are doing us a favor.
"They think that there will be mass hysteria; people will freak out and it will stop people going and doing their jobs. That's the only reason I can think of."
The four hour-long episodes are titled 'Caught on Tape', 'Seeing Is Believing', 'Worship & Abduction' and 'Sightings & Strange Cases'.