I enjoyed Series 1 more and had a much more thought provoking ending. I guessed the ending of Series 2 before the last episode. I would certainly buy the video. If you watch it, you will see a few links, to his daughter and his wife and the name of the main character in series 1.
I second the view that Nesbitt was brilliant in it. It's all to do with the effect that the disappearance had on the family and he portrayed this accurately.
It was compulsive viewing( series 1) and good acting but the ending let it down for me. It seemed the writers didn't know how to finish it. Shame, because the rest of it was brilliant like the second series. Out of the two, 2nd series was best in my opinion.